Seminars and Colloquia at ESO Garching and on the campus

Gas giant exoplanets are exciting to study for providing us with the most detailed spectroscopic observations. In this seminar, I will pick a few representative gas giants with diverse orbital and thermal conditions. I will focus on the modeling effort, especially how we simulate their atmospheric composition and what we can learn from it. As part of the story, I will highlight our recent work on the first observational evidence of photochemistry on WASP-39 b from the ERS JWST program (see paper <https://arxiv.org/abs/2211.10490> here and the NASA release here <https://exoplanets.nasa.gov/news/1715/nasas-webb-reveals-an-exoplanet-atmosphere-as-never-seen-before/>). I will conclude with future prospects of modeling planetary atmospheres.

With the laser guide stars (LGS) becoming a common element of the adaptive optics (AO) systems today and in the future, knowing how much flux you can get at any time and how much variations you can expect is an important input in the design of an AO system. Numerous parameters are affecting the amount of flux available in return for LGSs, in addition to the atmosphere transmission itself: telescope pointing direction, Na column density, time of the year, the year itself, where you are on Earth, meteorites, and many more. The four LGSs of the Adaptive Optics Facility (AOF) on the UT4 telescope at Paranal have been in operation since mid-2016 and the regular logging of the flux detected by the LGS wavefront sensors of the GALACSI (Ground Atmospheric Layer Adaptive Corrector for Spectroscopic Imaging) AO module of the MUSE (Multi-Unit Spectroscopic Explorer) instrument allowed to gather useful statistics of the flux return over five years now. I will present here the processing of the flux data together with the environmental ones, and the investigation performed to analyse and understand the variations in short, mid, and long periods of time. The statistics of these variations are used to determine the year-by-year and month-by-month flux available for LGS-WFS sensors. These data allow determining the Na density available for LGS generation at different timescales, and the results obtained at Paranal can also be used for Armazones AO systems. These on-sky results also proved to be very valuable for the study of the possibility to split the LGS units on UT4 in the scope of the MAVIS (MCAO Assisted Visible Imager and Spectrograph) instrument. Furthermore, an attempt is made to connect these measurements with Na density analysis performed in the field of Earth atmosphere study, and provide a prediction of the available flux anywhere on Earth and at any time.

Knowledge of how discs evolve is key to understand planet-formation because it allows to connect the properties of Myr-old discs to those of the currently detected Gyr-old exoplanets. Two main disc evolution mechanisms are confronting at the moment: according to the viscous theory, angular momentum is conserved and redistributed through the disc, while in the MHD-wind scenario, powerful magneto-centrifugal winds remove angular momentum from the disc. The data-driven revolution brought about by ALMA and VLT made observationally inferred fluxes, sizes and accretion rates available for populations of discs at different ages. In my talk, I will discuss how such data can be used to benchmark evolutionary models, with particular reference to the case of dust, which is still the most easily observed and widely detected and resolved tracer in populations of discs. This is fundamental to choose the best future strategies to eventually distinguish between viscous and MHD-wind evolution. I will also discuss a number of complications due to interactions between discs and their surrounding environment that need to be taken into account for a proper comparison between models and data.

An intriguing tension in the measurements of the Hubble constant (H0, that sets the expansion rate of the Universe) has emerged in recent years.  Independent determinations of H0 are important to assess the tension, which if verified, would imply new physics beyond the standard cosmological model.  I will illustrate independent methods to measure H0, particularly strong gravitational lenses with measured time delays between the multiple images. Exciting discoveries of the first strongly lensed supernovae offer new opportunities for measuring H0, and I will present recent advances.  I will show the bright prospects of lensed supernovae as an independent and competitive cosmological probe.

Note: This will not be a tutorial but rather an explanation of what has gone into the classification tasks of Gaia so far, meaning very useful to interpret the info in the Gaia catalogues but not necessarily to reproduce the classifications, etc.

I will discuss, largely using the whiteboard and a few printout plots/graphics, the ideas behind a next-generation widefield 50-meter telescope design that could achieve mapping speeds roughly a million times faster than ALMA. Come and imagine what you could do with AtLAST in one year what you couldn't even begin to do with ALMA in our lifetimes. AtLAST has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 951815 (see https://cordis.europa.eu/project/id/951815), and ESO is one of the participants in this EU-funded design study.

Mg II resonance doubles are an excellent tool for the kinematics of cold medium. Furthermore, the line ratio of Mg II lines is suggested as the LyC tracer in the epoch of reionization through JWST. Because of the resonance nature, Mg II lines can experience scattering processes like Lya photons in the cold medium. Scattering allows us to get additional physical properties of the scattering medium. Even though the scattering cross-section of Mg II is slightly larger than that of Lya, Mg II photons are not much optically thick due to the small Mg II fraction ~ log Mg/H ~ -5.5. We develop a 3D Monte-Carlo Mg II - Lya radiative transfer simulation. This presentation shows a surface brightness profile, a spectrum, and an escaping fraction of Mg II compared with those of Lya.

The European Space Agency's Gaia space mission, launched in 2013, is designed to measure the brightnesses, colors, positions, distances, and motions (in three dimensions) of almost two billion of the Milky Way's hundred billion stars. These measurements are yielding new insights about the internal structure and formation history of the Milky Way, thanks in part to a series of increasingly comprehensive data releases that any member of the astronomical community can access. In this talk, I will introduce the Gaia mission and summarize the latest data release, Gaia DR3. This discussion will be complemented by highlights of the science results from the Gaia data releases, showcasing among others the impact of Gaia on solar system studies, the Milky Way's accretion and recent dynamical histories, and understanding matter in extreme states. I will conclude will a look ahead at the GaiaNIR mission.

Paper: https://arxiv.org/abs/2210.03522

Paper: https://arxiv.org/abs/2210.13571

The strongest HI absorbers, the damped Lyman-alpha absorbers (DLAs), in QSO spectra indicate the presence of a gas-rich galaxy close to, or along, the QSO sightline. Identifying the HI-selected galaxies associated with DLAs provides a unique opportunity to connect the properties of high-z galaxies to those of their circumgalactic mediums, as well as to identify and characterize galaxies without a luminosity bias. We have hence been using NOEMA, the JVLA, and ALMA to carry out searches for redshifted CO emission from galaxies associated with DLAs at z>~2.

Combining our results with ALMA studies from the literature, we find that the highest-metallicity DLAs tend to be associated with galaxies with very high molecular gas masses, > 5 x 10^10 solar masses, while the galaxies associated with lower-metallicity DLAs are not detected in their CO emission. We have also used the JVLA to detect, for the first time, CO(1-0) emission from high-z HI-selected galaxies, allowing us to measure the excitation of the mid-J CO rotational levels. We find that all four HI-selected galaxies at z>2 with CO(1-0) studies show high excitation of the mid-J CO rotational levels, with near-thermal excitation found in the two galaxies with CO(1-0) detections. The mid-J excitation in the HI-selected galaxies is consistent with that in main-sequence and sub-mm galaxies at z>2, but significantly higher than that in main-sequence galaxies at z<2. The CO-detected galaxies are faint in our HST NUV images, indicating that they are highly obscured objects.

Beginning in December 2019, approximately 70 T Tauri stars were observed at UV wavelengths through the Hubble UV Legacy Library of Young Stars as Essential Standards Director's Discretionary program (ULLYSES). These publicly available spectra provide critical observational constraints on UV irradiation of protoplanetary disks, a key driver of the gas phase chemistry that sets the initial conditions for planet formation. We use the HST data and radiative transfer models to reproduce the LyA emission seen by surface layers of the gas disks, which typically makes up the largest component of the total integrated UV flux. The model LyA flux available to photodissociate molecules like H2O, HCN, and CH3CN within disks with dust cavities and gaps varies by two orders of magnitude, and we explore how the spread might translate to observable chemical differences. We also investigate whether ultraviolet emission lines from UV-fluorescent H2 can be used to break the degeneracy between disk flaring angle and UV irradiation of the gas in models of sub-mm CN emission. This work will be particularly useful for interpreting molecular features in spatially unresolved disks observed with ALMA and JWST.

The physics of hadrons, nuclei and nuclear matter can be described in terms of pertinent effective eld theories, here chiral dynamics in various settings. In this talk, I highlight some of the important works done by Norbert Kaiser and Wolfram Weise in this eld. Topics include the enigmatic Λ(1405) baryon, the nuclear force problem and strangeness nuclear physics.

Understanding the processes that regulate star formation in galaxies remains at the heart of modern extra-galactic astronomy, and debate continues as to why some galaxies exhibit powerful starbursts whilst others are largely dormant.  The key to progress in this arena lies with assembling large, diverse samples of galaxies for which we can measure all of the critical ingredients, such as the current star formation rate (SFR) and gas content.  However, it is insufficient to simply measure global galactic quantities, as we know that a given galaxy will manifest considerable internal diversity in its star formation activity.  It is therefore essential to study gas and star formation on spatially resolved scales.  The ALMA-MaNGA QUEnching and STar formation (ALMaQUEST) survey combines maps of stellar properties obtained from the MaNGA (optical) integral field unit survey with ALMA CO (1-0) maps on a common kpc-scale grid, in order to tackle questions of star formation in local galaxies.  The 46 galaxies in the ALMaQUEST sample span a wide range of SFRs, including both normal star forming galaxies, as well as those both on their way to quenching, and those undergoing starbursts.  In this talk, I will present the ALMaQUEST view of understanding the interplay of gas and star formation across this broad galactic landscape.

Paper: https://arxiv.org/abs/2210.15486

The Pyramid sensor (Ragazzoni, 1996) is the reference for Single Conjugate Adaptive Optics. We revisit the concept of dual channel 2-sided Pyramid sensor (Phillion, 2006) and generalize it into the new class of the Bi-Orthogonal Foucault knife-edge sensor (Bi-O- edge). We propose innovative opto-mechanical concepts that allow to get rid of the dynamic beam modulation. We compare the properties of the Bi-O-edge with the Pyramid using the Convolutional model (Fauvarque, 2019) and end-to-end simulations.

Thanks to the analytical tool, we show that the nature of the measurements of the Pyramid and the Bi-O-edge exhibit significant differences. In particular, we show that depending on the number of degrees of freedom, the Bi-O-edge can outperform the Pyramid in terms of sensitivity. Taking an eXtreme AO application (e.g. PCS on the ELT), we show that the Bi-O-edge sensitivity gain can exceed one stellar magnitude.

Last but not least, the spatial resolution of the Bi-O-edge can be extended by a factor of 2 thanks to a super-resolution capability (Oberti, 2022) that surpasses dramatically the one of the Pyramid.

The Enhanced Resolution Imager and Spectrograph (ERIS) is mounted on UT4 on Paranal and recently the commissioning came to an end. Science Verification will start beginning of December and regular science observing in April 2023.

The instrument separates into the near-IR integral field unit SPIFFIER which is an enhanced version of the former SINFONI instrument and an imaging camera called NIX reaching out to M-band. NIX features also several coronographic modes and a long slit for L-band.

We will describe the different instrument modes and the enhanced use of the AO using the deformable mirror. We will then discuss some possible science cases and hopefully get you thinking about what you could do with ERIS.

Astronomy's current model of galaxy evolution is built on a foundation of hierarchical growth, in which small galaxies merge together to form larger ones.  In addition to the simple accrual of mass, this merging process is predicted to fundamentally change the galaxie' properties, such as dramatic morphological transformations, the triggering of bursts of star formation and high rates of accretion onto the central supermassive black hole.  In this talk I will explain the physical processes behind these predictions, and present the observations that we are performing in order to test the theory.  Although many of the predictions are indeed borne out by experiment, there have been some surprising conflicts as well, that demand revisions to our models of how mergers shape galaxy evolution.

In the last few years, there has been a rise in the discovery of streamers, which are long gas structures (~ 1000-10000 au) that feed the protostellar disk and/or pseudodisk region with material from both within and outside their natal core. This newly observed infall mechanism goes against the classical picture of star formation, where accretion into the protostar and protoplanetary disk is azimuthally symmetric and relatively isolated from external influences. Streamers have been found in multiple phases of star formation, from the deeply embedded Class 0 phase to the unveiled Class II phase. In this talk, I will present our current knowledge of streamers and present two new members to our collection, found toward Class I protostars using ALMA and NOEMA observations. I will show how we characterise the gas kinematic signatures with a simple analytic solution for free-fall motion. It is only thanks to the combination of several tracers that enables for a better understanding of the mass delivery process to disk scales. I will finally discuss the possible effects of these streamers in protostellar disks and how they could connect to the large-scale filaments and fibers. These newfound streamers and asymmetries in the dense core highlight the importance of the local environment beyond the embedded phase of star formation.

The use of plasmonics and photonics to control light and heat close to the thermodynamic limit enables exciting opportunities for nanoscale energy conversion. The efcient harvesting and conversion of photons into photons of a different energy, phonons or energetic charge carriers open up a myriad of opportunities for converting, for example sunlight, into fuels, heat and light. By employing articially structured materials (metamaterials), hybrid plasmonic colloids, dielectric nanoresonators or engineered metal nanoantennas, I will show different approaches for converting energy by controlling, tuning and enhancing light-matter interactions.

Massive stars are fascinating objects that are still poorly understood.  Yet, they play a central role in many topical questions in astrophysics. These range from questions about enrichment and feedback in distant galaxies where they dominate the light (now probed by JWST), to questions about their violent deaths given rise to diverse transient (soon to be probed by the Rubin observatory), to questions about the compact remnants they leave behind (now detected through gravitational waves).  In this seminar, I will provide a general introduction and show examples of work by early career researchers that have been active in our group.  With this, I hope to share a taste of the excitement about recent insights, with the appropriate humbleness for the physical processes we still do not understand.

The formation of the first galaxies in the Universe is the new frontier of both galaxy formation and reionization studies. In fact, we will soon directly observe primeval galaxies thanks to the James Webb Space Telescope, and witness the reionization process through 21cm intensity mapping experiments. This unique moment in human history creates a fierce new challenge, i.e. to simultaneously understand in a unique and coherent picture the processes of galaxy formation and reionization, and – crucially – their connection. The latter, in particular, has escaped past numerical efforts. In this talk I will present the outcome of an years-long effort geared toward achieving such comprehensive picture, culminated in the Thesan suite of cosmological radiation-magneto-hydrodynamical simulations. They are unique for a number of reasons, namely they: (i) cover a very broad range of spatial and temporal scales, connecting cosmic reionization with galaxy formation; (ii) simulate an unprecedentedly-broad range of physical processes for simulation of such scales and resolution, including stellar and black hole feedback, individual metals transport, galactic winds, dust creation and destruction, self-consistent radiation transport from stars and black holes,and magnetic fields; (iii) exploit knowledge accumulated at low redshift to minimize the number of free parameters in the physical model; (iv) use a variance-suppression technique in the production of initial conditions to increase their statistical fidelity; (v) includes multiple runs exploring current unknowns in the physics of dark matter and ionizing sources. I will finally show an example of how Thesan is informing observations of the high-z IGM-galaxy connection.

The birth of the first stars, black holes and galaxies heralded the end of the cosmic Dark Ages and the beginning of the Cosmic Dawn. The light from these objects heated and ionized almost every atom in existence, culminating in the Epoch of Reionization (EoR): the final major phase change of the Universe. This final frontier of astrophysical cosmology is undergoing a transition from an observationally-starved epoch to a "Big Data" field. This process is set to culminate with upcoming observations of the redshifted 21-cm line: providing a 3D map of the first billion years of our Universe. The patterns in these maps are driven by UV and X-ray radiation from the first galaxies, as well as physical cosmology. I will showcase a Bayesian, data-driven, forward-modeling framework to understanding astrophysics and cosmology from the Cosmic Dawn. I will demonstrate how preliminary 21-cm data from the Hydrogen Epoch of Reionization Array (HERA), when combined with other EoR and galaxy observations, already constrain the heating and ionization history of the Universe. High mass X-ray binaries (HMXBs) are mostly likely responsible for heating the intergalactic medium before the EoR, and current HERA limits imply that the first HMXBs were more luminous than local ones, consistent with theoretical arguments based on binary evolution in low metallicity environments.

This is a story about how machine learning is enabling us to do bigger, bolder, and more robust Bayesian analyses.

Inferring the properties of the galaxy population in the Universe over cosmic time is of central importance in extragalactic astronomy, both for understanding galaxy evolution, and for enabling us to constrain cosmology and fundamental physics from large-scale structure (via weak lensing and galaxy clustering measurements). The task at hand sounds simple: given an observed galaxy catalogue of measured photometry or spectra, how do we constrain the redshift-evolving properties of the galaxy population? As it happens, this is a really hard problem for a few reasons: (1) parameterising the galaxy population so that it fully encompasses galaxy evolution phenomenology is really hard, (2) the stellar population synthesis (SPS) models relating galaxy physical properties to their observables (spectra and photometry) are too expensive to run at scale for millions of galaxies, (3) both photometric and spectroscopic data have non-trivial data-calibration effects that need carefully accounting for, and finally, (4) even if you could solve 1-3, galaxy surveys are always subject to selection effects, making the likelihood function intractable, so none of the standard Bayesian methodology is applicable anyway. In this talk I will show you how, enabled by recent advances in machine learning, we can now do the galaxy-survey analyses of our dreams: full Bayesian hierarchical analysis, with all the gore.
 

Paper: https://arxiv.org/abs/2102.11676

I will present recent results from the Keck Planet Imager and Characterizer (KPIC), a pathfinder diffraction-limited fiber-fed high-resolution infrared spectroscopic facility at Keck Observatory. KPIC includes an infrared pyramid wavefront sensor using an e-APD SAPHIRA detector and a fiber injection unit designed to couple light from a high-contrast off-axis exoplanet into a single-mode fiber connected to the near-infrared high-resolution spectrograph NIRSPEC. KPIC's successful single-mode fiber coupling demonstration forms the basis of two future instruments: Keck-HISPEC and TMT-MODHIS, which are undergoing preliminary and conceptual design phases, respectively. HISPEC and MODHIS will provide diffraction-limited R=100,000 spectroscopic capabilities in the near infrared from 0.96 to 2.45 microns simultaneously, enabling exciting applications in exoplanet science (high contrast spectroscopy of directly imaged exoplanets, transit/close-in exoplanet spectroscopy, and precision radial velocities).

The study of the filamentary nature of the Interstellar Medium  has been revolutionized by the use of ALMA’s high-resolution observations. However, the analysis of interferometric data is not straightforward, as the emission properties of the observed sources include large regions with diffuse, extended emission, strongly affected by the interferometric filtering effects on the true sky brightness distribution. We aim to quantify the impact of instrumental effects on the recovery of these fundamental filamentary structures at different spatial scales in the ISM by detailed simulations. Our results quantitatively illustrate the intrinsic limitations of interferometers for the recovery of sources such as cores and filaments with extended emission, both not recovering the total emission of the source and critically affecting the radius and the slope of their true radial profile.  In our work we investigate different data-combination methods, comparing the results obtained from the combination of the ALMA 12m array data with the ALMA short-spacing contribution (ALMA 7m array and Total Power) and a with a large Single Dish image.

Single-lined spectroscopic (SB1) O-type binaries are ideal objects to search for elusive black hole (BH) companions and are indispensable for establishing the natal mass ratio distribution of stars. In this talk, I will present an overview of the binary properties of the massive stellar content of the Tarantula nebula of the Large Magellanic Cloud, focusing on recent work on the SB1 population using the technique of spectral disentangling. I will discuss new results regarding the mass-ratio distribution of massive stars at sub-solar metallicity, and present results for the first dormant black hole ever uncovered outside our Galaxy.

Many processes during the evolution of protoplanetary disks and during planet formation are highly sensitive to the sizes of dust particles involved: the efficiency of dust accretion in the disk, gravoturbulent instabilities leading to the formation of planetesimals, or the accretion of pebbles onto large planetary embryos to form giant planets are typical examples. Furthermore, radiative properties like absorption or scattering opacities depend on the particle sizes. In this talk I will demonstrate how we are simulating dust growth in protoplanetary disks using our dust evolution software DustPy and I will highlight some research projects that have been done with it.

The Sun is often used as a standard for studying low-mass stars. We have more data on the Sun than we can ever hope to obtain for other stars. These data have allowed us to determine the internal structure of the Sun with great precision, which has allowed us to test the theory of stellar structure and evolution and test physical processes. The multi-decade helioseismic data sets also allow us to study changes in the Sun.

In this talk, I shall describe how seismic data have allowed us to use the Sun as a laboratory to study physical processes as well as fundamental properties of matter. I shall also describe how the Sun changes over the solar activity cycle and how the changes are posing challenges to theory.

Papers:

https://arxiv.org/abs/2104.04259

https://arxiv.org/abs/2101.02654

In this colloquium, I will discuss the aims and current status of research on exoplanet atmospheres. In particular the focus will be on ground-based techniques and results. I will also discuss the first isotope measurements in exoplanet atmospheres and what they may tell us of planet formation and evolution. The ELT provides extremely exciting prospects.

Paper: https://arxiv.org/abs/2210.04934

All the First Light instruments of the ELT will embed an Adaptive Optics (AO) mode to compensate for the optical aberrations due to the atmospheric turbulence. From the AO perspective, the complexity of these instruments as well as the colossal structure of the ELT provides a new and challenging environment to calibrate and operate these AO systems.

To maximize the scientific return of the telescope, these technical specificities compel us to optimize both the calibration and the control strategies of the AO instruments before and during the observations. In this presentation, I will provide an overview of the challenges that will be faced by the First Light instruments on their road to a stable and efficient AO control.

The focus will be done on SCAO systems equipped with Pyramid Wave-Front Sensors. A particular attention will be given to the calibration of the mis-registrations (relative evolution of the M4-WFS registration due to mechanical flexures). To do so, we recently proposed the SPRINT method that consists of acquiring a few on-sky signals to track the mis-registrations. An experimental validation achieved on the GHOST bench at ESO as well as at the VLT-GRAAL instrument will be presented to demonstrate the high precision of the proposed method.

Dust is found frequently in early-type galaxies. The traditional view that dust is mainly produced by young stellar populations, can only be rescued if dust in old stellar populations would have an "external origin" (whatever that means). I shall show a gallery of dust manifestations in various galaxies. A few galaxies like NGC 1316, NGC 4696, and NGC 5102 will be presented in more detail with regard to their dust and gas content. The lesson to be learned is that apparently a significant part of the dust is produced and distributed internally, by dusty winds from nuclei and/or by dust formation in magnetic field structures.

The Standard Model of nature's laws provides no explanation for the fundamental constants, like electromagnetism's strength, alpha. It is therefore up to experiments to test whether fundamental constants are, indeed, constant and universal, or instead vary and depend on other physical parameters. I will describe a new probe of alpha's constancy within our Galaxy, solar twin stars, and show our first results which have an ensemble precision of 12 parts-per-billion. This is already the best astronomical measurement of any fundamental constant so far. The results derive from archival high-resolution optical spectra (HARPS) from the ESO 3.6-m telescope, so there is considerable scope for extending them using larger facilities. Our goal is to map alpha across the Milky Way and, importantly, its widely-varying dark matter density field. This will be a completely new, direct test of physics beyond the Standard Model. I will report our discovery of the most distant solar twins and analogues, up to 4kpc closer to the Galactic Centre, as the first step towards that goal, and outline current and future work.

I will report on the very recent discovery of a Fast Radio Burst (FRB) localised to a galaxy at redshift z=1.02. This FRB host galaxy is twice as distant as any previously identified FRB host galaxy (all of which are at z < 0.5). In my talk, I will give a brief introduction to the FRB phenomenon and explain why these enigmatic objects are of interest in areas as diverse as stellar astrophysics, galaxy evolution and cosmology.

I will also describe the recent ESO observations that allowed our team to identify and study the host galaxy of this very distant FRB and will outline some of the key astrophysical questions (both observational and theoretical) that remain unanswered.

The origin of high-energy neutrinos is fundamental to our understanding of the Universe. Apart from the technical challenges of operating detectors deep below ice, oceans, and lakes, the phenomenological challenges are even greater. The sources are unknown, unpredictable, and we lack clear signatures. Neutrino astronomy therefore represents the greatest challenge faced by the astronomy and physics communities thus far. Immense effort has been put into identifying galactic and extragalactic sources of TeV-PeV neutrinos but still to no avail. I will discuss recently results and our current efforts in understanding the highest energy particle processes in the Universe.

Dust attenuation will be key for interpreting high redshift galaxies observed by HST+JWST, yet the connection between the amount of stellar light lost to dust in the UV-optical and the dust emission recovered in the IR, while being perfectly understood theoretically, is still ill quantified observationally. Much of the ambiguity stems from the degeneracy between the effects of dust attenuation and the ageing of stellar populations on the observed spectral energy distributions of galaxies. When joined with line-of-sight effects from the patchy dust distribution in galaxies, this degeneracy prevents the derivation of general dust attenuation curves for use on the spectral energy distributions of high redshift galaxies. During this talk, I will attempt to briefly summarize the current state of this area of study and propose directions for future progress.

Agenda

~30min talk:

• Choosing where to apply
• Components of an application
• Talk tour
• Timeline
• Job interviews
• Making decisions

~30min Q & A session

Gas flows in and out of galaxies are typically probed by quasar absorption lines which are usually limited to a single sightline through the halo, giving no information on the structure of the gas probed in absorption. First studies using lensed, multiple or extended background objects have shown that there can be significant variation of absorber strengths on relatively small (~kpc and less) scales, hinting at an inhomogeneous clumpy circum-galactic medium. I am going to present our ongoing efforts of combining observational IFU data of lensed quasars with high spatial resolution cosmological simulations in order to study the small-scale structure of the CGM. I will show the results of our non-targeted "blind" search for intermediate absorbers and their metal line variations over kpc scales using MUSE data of a lensed quasar field. To learn more about the underlying physical structure of the gas probed in the CGM, I am using FOGGIE's highly resolved cosmological simulations to extract and analyse the clumps and filaments in galactic halos and I will report on the current state of our efforts to mock and interpret observables from these simulations.  

The cosmic web is a complex network of structures that fills the Universe, composed of galaxy clusters at the nodes, connected among them by filaments and separated by large voids. Filaments are elongated, one-dimensional structures which are much more elusive than clusters due to their lower density. The advent of wide-area, large-scale spectroscopic galaxy surveys has allowed us to start investigating the properties of the filaments (and of the cosmic web in general) and to understand their nature. In particular, how filaments connect to clusters and how these connections impact cluster evolution is a hot topic in astrophysics. The average connectivity (number of connected filaments) of a few observed and simulated cluster samples has been measured and it has been demonstrated that it scales with cluster mass. Filaments connecting to clusters have also been detected in the gas phase, either as bridges of matter connecting pairs of clusters or as the tip of gas structures visible at large radii from the cluster center in X-ray observations. In Malavasi et al. 2020, we applied a cosmic web detection algorithm (DisPerSE) to the Sloan Digital Sky Survey (SDSS) to detect the filaments of the cosmic web from the galaxy distribution. We then looked at the position of the Coma cluster of galaxies and we detected three secure filaments connecting to the cluster. This discovery lead to the developing of a further investigation based on constrained numerical simulations. This kind of simulations allow to reproduce in detail a portion of the nearby Universe, recreating observed clusters including Coma. We are currently performing an analysis of these simulations, aimed at reproducing the observed distribution of the filaments connected to Coma with the aim of studying their evolution throughout cosmic history and determining the impact of matter accretion channeled through these structures on the evolution of the Coma cluster. In this talk I will review the results of Malavasi et al. 2020 and introduce the results we obtained with the study of our constrained numerical simulations.

To model the formation of planets, we need reliable initial conditions for the gaseous disk constrained from observations. However, most precise data is available for evolved Class II objects and their dust content. Therefore, we follow a disk population synthesis approach with dust evolution and in an exploratory project also inverted the approach to retrieve initial dust properties and the disk evolution parameters from Class II observations given our disk evolution model. With these exercises, we show that for a standard, simple viscous alpha disk model with photoevaporation, it is challenging to match accretion luminosities and millimeter fluxes for the given stellar mass.

The origin of stellar masses, arguably the most central question in star formation remains a major open issue in modern astrophysics (see review by, e.g., Ballesteros-Paredes et al. 2020). The main goal of the ALMA-IMF Large Program (PIs Motte, Ginsburg, Louvet, & Sanhueza) is to determine how the origin of the initial mass function (IMF) is in fact dependent on cloud characteristics or not. Thanks to its unmatched angular resolution, sensitivity, image quality, and excellent frequency coverage, we used ALMA to survey 15 massive protoclusters, covering a wide variety of Galactic environments and evolutionary stages (Motte et al. 2022). I will present recent ALMA-IMF results (Motte et al. 2018a; Pouteau2022; Nony et al. subm.; Louvet et al. in prep.) that show that the mass distributions of the >600 detected cores (CMFs) in these typical yet extreme environments of the Milky Way present an excess of high-mass cores with respect to the canonical IMF (e.g., Kroupa et al. 2013). A detailed study of two contiguous protoclusters, W43-MM2 and W43-MM3, which are at different evolutionary stages suggests that the CMF deviates from the canonical IMF form when and where a burst of star formation develops (Pouteau et al. subm.). The CMF would thus strongly depend on environmental parameters and may lead to non-universal stellar IMFs and heterogenous, potentially mass-segregated spatial distribution of stars.

In addition, the ALMA-IMF Large Program aims to discriminate between the quasi-static and dynamic scenarios by quantifying the role of cloud and core kinematics in defining core mass and in how this changes over time. I will present initial results on the dynamical properties of cores using the DCN line emission along with the gas kinematics extracted from the dense gas tracer N2H+. ALMA-IMF also provides the community with an unprecedented database (Ginsburg et al. 2022; Cunningham et al. in prep.) with high legacy value for protocluster clouds (60 pc2 at 2000 AU resolution), cores (about 1500 cores with 0.15-250 Msun masses), many of which are associated with outflows, filaments (hundreds of star-forming filaments), often tracing gas inflows, and hot cores (several tens of hot cores).

The Milky Way's centre is the closest galaxy nucleus and our Galaxy's most extreme environment. In spite of occupying less than 1% of the Galactic disc's volume, this region was responsible for up to 10% of the entire Milky Way's star forming activity over the past 100 Myr. Therefore, the Galactic centre is the most active star forming region of the Milky Way when averaged over volume, constituting a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, there are only two known young clusters at the Galactic centre, that account for <10% of the expected young stellar mass. In this talk I will discuss the challenges hampering the observation of the Galactic centre and will present our results on the Sagittarius B1 region, where we find evidence for the presence of several 105 solar masses of young stars that formed ~10 Myr ago. This is a large step towards a more complete census of young stars and opens the field for a better understanding of star formation at the Galactic centre, such as the fate of young clusters and the possibly different initial mass function in this region.

In eccentric binary systems, circum-binary discs that are sufficiently inclined to the binary orbital plane align in a perpendicular configuration (called polar configuration) with respect to the binary plane. In hierarchical systems with more than two stars, polar alignment is studied with pure binary criteria. Recently, we showed analytically and numerically that pure binary criteria for polar alignment are necessary but not sufficient for polar alignment in hierarchical systems. In this talk, I will present the generalized criteria and I will compare the observed distribution of disc inclinations in the binary and in the hierarchical system populations. I will show that how disc inclinations are distributed in stellar populations strongly depends on the multiplicity of the systems and thus, better understanding alignment conditions in hierarchical systems is critical in order to well interpret these data.

Paper: https://arxiv.org/abs/2209.02489

Static and quasi-static aberrations afflict all imaging systems on large telescopes, worsening the PSF and in this way limiting the contrast achievable. Most of them are corrected as offset on the AO system, but some of them are left uncorrected because they are on a different optical path from the Wavefront sensor of the AO system. For this reason they are called Non-common path aberrations (NCPA). I worked on a new method based on a combination of a Principal Component Analysis and a Multilayer Perceptron Neural Network for image recognition using slightly defocused images to measure and correct for them. This innovative approach is based on the use of Principal Component weights and Principal Component eigenimages coming from a simulated images dataset. Every experimental image is reprojected on this basis and the corresponding coefficients are used to retrieve the relationship between the intensity in the image plane and the phase in the pupil plane, encoded through Zernike amplitude coefficients. In this talk I will show the first results on the GHOST bench where I introduced aberrations through a Spatial Light Modulator, measure the NCPA through the NN and compensate for them injecting those values found back in the SLM. Using iterative process of prediction and correction in just few steps it is possible to recover almost completely the PSF. This method could represent a new concept for low order wavefront sensors.

The Large and Small Magellanic Clouds provide the closest example of a galactic “three-body train wreck” in the local Universe. In fact, several stellar substructures, based on photometry and/or proper motions, have been uncovered in the outskirts of the Clouds, evidence of past interactions between the two dwarfs, and disturbances due to the Milky Way's tidal field. Mira variables are long-period pulsating red giant stars, bright enough to trace the Magellanic outskirts with precise Gaia eDR3 proper motions. In this talk, I will present a spectroscopic campaign to derive radial velocities for tens of Mira stars in the Magellanic periphery. On-sky position, distances from period-luminosity relations, and 3D velocities were used to elucidate the origin of these tracers and their observables. Using a suite of dynamical models for the past interactions of the Clouds, a recent disk-crossing of the SMC, largely disturbing the east side of the LMC, successfully reproduces the observed properties of the Mira stars. The implications of our findings will be discussed.

Many molecules have been observed in protoplanetary disks with ALMA, but each molecule probes a different part of the disk. Understanding the full 2D temperature and density structure in a protoplanetary disk is crucial to understand planet formation. For example, planet formation is expected to be enhanced at the water snowline, the midplane radius where water freezes-out. The water snowline can be traced with HCO+, a molecule that very strongly reacts to the desorption of water. In this talk I'll discuss how HCO+ can be used to find the water snowline. Furthermore, I'll use the rarely observed 13CO J=6-5 transition to measure the temperature in the cavities of transition disks and find out if planets could be carving these deep cavities.

Star formation and planet formation are genuinely intervowen processes. This tight interconnection largely occurs through the formation of circumstellar and protoplanetary disks. While it has since long been recognised that disks would naturally be explained by the conservation of angular momentum during the collapse of the dense core, several teams have recently stressed, that  due to  efficient magnetic braking, magnetic field is likely playing a crucial role regarding the formation of disks. How this exactly occurs, has however turned out to be rather complicated. This is because on the one hand, magnetic braking has been found to depend on the dynamical state of the collapsing dense core, namely the geometry and intensity of the magnetic field but also the strength of the turbulence. On the other hand, the efficiency of magnetic braking also depends on the ionisation degree and on the charge carriers, the dust grains. None of these processes are really well understood.

During the talk, I will review the subject discussing various simulations, as well as analytical efforts, which have been performed along the years to decipher the respective influence of physics and initial conditions. This goes from highly idealised isolated dense cores to massive clusters. I will also present comparisons between observations and simulations. Finally, I will discuss two important issues, the strong dependence of disk properties in the numerical scheme, namely the sink particles and the possible high level of ionisation seemingly measured within a few dense cores.

Paper: https://arxiv.org/abs/2206.11174

During the past years, ESO developed an ultra-fast Shack Hartman (SH) WaveFront Sensor (WFS) based on using a highspeed camera at framerates as high as 16 kHz. This WFS has been used to characterize the sub-ms spatio-temporal behaviour of Deformable Mirrors. This paper reports about the results obtained with micro voice coil actuated Deformable Mirrors. At sampling rates up to 16 kHz fast transients of the full surface can be measured allowing for detailed characterization and modelling of the mirrors’ spatio-temporal behaviour. When an optical phase step is applied to an actuator it triggers a wave travelling across the surface to the edges and then reflected. Using the fast WFS developed by ESO, it has been possible to visualize and characterize this transient phenomenon. Based on these experimental observations, different feed forward control techniques are designed and their efficiency to improve the actuators temporal behaviour and reduce the amplitude of the parasitic surface waves are compared.

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12185/1218526/ESOs-ultra-fast-wavefront-sensor-unveils-the-mysteries-of-deformable/10.1117/12.2627917.full

Stochastic variability in active galactic nuclei (AGN) hosting supermassive black holes is ubiquitous across wavelengths and timescales. Unlike X-ray variability studies, measurements of high-quality optical light curves and power spectra of AGN are just beginning. A key question is if AGN variability properties can be related to physical properties of the accretion disk. In this talk, I will show our recent results demonstrating the characteristic “damping” timescale of AGN optical light curves correlates strongly with the mass of the black hole. Extension to stellar-mass accretion disks suggests the interpretation may be universal, and could be a powerful new tool for identifying the elusive population of accreting intermediate-mass black holes. 

The discovery of the first exo-planet around a sun-like star in 1995 revolutionized Astronomy. In just ~25 years, we went from not knowing if the Solar system is a fluke of Nature to realizing that it is totally normal for stars to have planets. It is now clear that planet formation is a robust process, as planets are found around stars more and less massive than the Sun and as planetary systems have been identified in increasingly complex architectures, including other 8-planet systems or planets around binary stars. Relating this diversity of planetary systems to their formation is now a major research area, attracting worldwide large investments in new facilities and staff. The overall objective of the Nucleus for Planet Formation (NPF, of which I was the director until April) is to obtain a better understanding of the planet formation process that will finally allow us to predict what type of planetary systems form under which conditions. We tackle this goal by combining all three branches of modern astronomy: observational and theoretical astrophysics, as well as the technical development of new astronomical facilities. This approach had not only the goal to bring us closer to answering fundamental scientific questions, but also help to convert Chile from a nearly pure user of the astronomical facilities built in the country to a fully grown up and internationally acknowledged partner in all aspects of modern astronomy. In this talk I will highlight some of the results produced by the members of NPF between the end of 2017 and now.

Paper: https://arxiv.org/pdf/2208.13768.pdf

High-mass X-ray binaries (HMXBs) are systems consisting of a compact object (neutron star or black hole) with a relatively massive star. About a third of them are considered to be emitting X-rays by accreting part of the wind emitted from the donor star, and only a handful of them are known to host black holes. The amount of accretion is usually estimated by using the Bondi-Hoyle accretion model with an assumed velocity distribution and mass-loss rate for the wind. It is usually also assumed that the wind is spherically symmetric, which is true as long as the wind is faster than the orbital velocity. However, if this assumption holds, the wind flows symmetrically around the black hole and therefore there is insufficient angular momentum in the accreted material to form an accretion disk and emit X-rays. In this study, we model the wind acceleration process in close binary stars where the wind velocity can be slower or be comparable to the orbital velocity. We find that due to the tidal force from the companion and the associated deformation of the donor star, the wind can have a highly asymmetric velocity distribution. This strongly influences the amount of angular momentum that accretes onto the black hole, enabling accretion disk formation. There is a strong orbital separation dependence for this effect, and we predict that accretion disks cannot be formed when the Roche lobe filling factor of the donor is less than ~80%.

Star formation in our Galaxy typically occurs in low and intermediate-mass environments counting a few 10^2, 10^3 stars. However, a few more extreme star forming environments exist, where hundreds of thousands to millions of stars form in dense regions, often in single events of star formation. Often called “starburst regions”, they are quite rare in our Galaxy today, with a few examples known, while they are common in galaxies experiencing epochs of intense star formation activity (such as interacting galaxies) and in the early Universe.

With a distance of 3.87 kpc from the Sun, and an estimated initial mass of 52000 solar masses, Westerlund 1 is the closest starburst cluster to the Sun. It offers the unique possibility to study star and planet formation, the early stellar evolution and the physics of compact objects in a starburst environment.

In this talk I will present the EWOCS project (Extended Westerlund One Chandra, and JWST, Survey) which is based on a 1Msec Chandra/ACIS-I Large Project, oncoming JWST observations of Westerlund 1, and other data at high spatial resolution (GEMS/GSAOI, HST, etc..). I will discuss the objectives of the project and present the status of the art of data analysis.

Protoplanetary discs are the place where planets form and evolve. It is then fundamental to study their evolution to fully characterize the process of exoplanetary system formation. Discs can be studied using two different approaches: on one side, they can be analysed as a set of single sources, understanding in detail which are the mechanisms responsible for the huge variety of morphologies (rings, gaps, ..) observed in the recent observations. On the other side, it is also important to study regions of star formation, understanding which physical processes are governing the global disc evolution.  In this talk, I will firstly describe results from the modelling of single sources, underlining the information we can obtain by comparing multi-wavelengths observations with results from the hydrodynamical models of specific sources (e.g., HD169142, PDS70). I will then summarize some of the results obtained by testing disc evolution models by comparing them with the Lupus star forming region. In these works, we tested the secular evolution of the observed dust and gas radius of disc populations and their ratio, to test the efficiency of radial drift and the viscous evolution theory.

National Optical-Infrared Astronomy Research Laboratory is the US national center for ground-based, nighttime optical and infrared astronomy. This integrated and distributed center consists of the Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), Gemini Observatory, Kitt Peak National Observatory (KPNO) and soon the Vera C. Rubin Observatory (formally known as LSST) once it enters operations. 

Michiel van der Hoeven, director of engineering services, will provide an overview of this organizational transformation and show some examples of the processes the engineering team has used and applied to help form this new organization. 

The Near InfraRed Planet Searcher (NIRPS) instrument is offered to the community for the first time at the upcoming ESO Call for Proposals (27th of Sep 2022). NIRPS is a near-infrared, high-resolution spectrograph equipped with an adaptive optic system and optimised to reach a long-term stability of < 1 m/s. The mission of NIRPS is to search for new exoplanets around the Milky Way’s coolest stars. The instrument will focus its search on rocky worlds, which are key targets for understanding how planets form and evolve, and are the most likely planets where life may develop. NIRPS will search for exoplanets using the radial velocity method and characterise exoplanet atmospheres with transmission spectroscopy. This informal discussion aims at presenting the instrument capabilities, detailing its science goals and answering any questions you might have to help you shape your NIRPS science projects.

The Antikythera Mechanism is the first computer in human history. Built during the 2nd century BC, it was retrieved in 1901 from an ancient shipwreck and is nowadays partially preserved in 82 petrified and fragile fragments. Its functions and use remained a mystery until recently. With the use of innovative techniques, we now know that it was a mechanical model of the cosmos, an advanced machine that displayed the position of the Sun, the Moon and the five naked-eye planets on the sky. The recently formed solar, lunar and first planetary theories of ancient greek astronomy were converted into elaborate axles and gears that calculated the exact positions of the celestial bodies. To its basic function, many more had been added, such as a lunisolar and an astronomical calendar and the prediction of eclipses, resulting in a highly complex machine, fully covered with dials, pointers and texts. The Antikythera Mechanism is nowadays the unique preserved artefact of the technical sophistication that these models of the cosmos finally reached.

High-resolution observations from the last decade show that protoplanetary discs are very complex objects. Rather than uniform discs, we see that they have large cavities, spiral arms, rings, gaps, and asymmetries. To understand these features, astrophysicists many times have to develop numerical simulations, in which planets or unseen stellar companions are added to reproduce the observed morphologies. While the spectacular observed images are popular in mainstream media, the simulation side is rarely known by the general public.
We have created "Protoplanet express", a video game in which the user visits different known protoplanetary discs, which are rendered in 3D from actual hydrodynamical simulations. The user will encounter in the models the same features observed with telescopes, and their goal will be to find the reason for each of them. For example, the user completes a level once they find the planet causing an observable gap in the disc.
In this presentation I will show excerpts from the game, discuss its development, and upcoming release.

References:

https://arxiv.org/abs/2004.12419

https://asmitabhandare.github.io/

Paper: https://arxiv.org/abs/2102.07963

Turbulence is essential to many fundamental processes in protoplanetary disks, including angular momentum transport, dust evolution, and planet migration. I will focus on two instabilities that can drive turbulent motions in outer disks. In the first part of this talk, a series of global 3D non-ideal MHD simulations via Athena++ code will be presented. The outer disk is found to be weakly MRI turbulent, and annular substructures arise due to magnetic flux concentration. The weak MRI turbulence permits the growth of the vertical shear instability. In the second part of this talk, the saturation of the vertical shear instability mediated via parametric instability will be covered. Once the parametric instability prevails, it is anticipated that the vertical shear instability is far more incoherent than extant published simulations suggest.

Paper: https://arxiv.org/abs/2204.05636

I will describe recent results in our efforts to 'observe' cosmological hydrodynamical simulations, with a particular emphasis on the low-density gas in the Universe, from the circumgalactic medium (CGM) around galaxies to the intergalactic cosmic web. Forward modeling lets us create synthetic observations: to test the simulations, interpret recent data, and guide future observations. In particular, emission from hydrogen and metals in diffuse gaseous components is a powerful probe. Combining the IllustrisTNG simulations with resonant line radiative transfer modeling we study predictions for extended Lyman-alpha and MgII halos around galaxies, and the chance to 'directly image' the cosmic web in emission, with an eye towards observability with instruments such as VLT/MUSE, Keck/KCWI, and HET/VIRUS.
 

Current protostellar evolution models often consider protostellar disks as isolated objects, but interactions between disks and passing-by stars should be frequent especially in protoclusters. Such interactions, or better known as 'flybys', have been suggested for protoplanetary disks surrounding low-mass protostars. Here we extend this paradigm to massive star forming regions, and find that flybys are also impacting the evolution of a massive disk surrounding an early O-type protostar. Using high sensitivity, high resolution ALMA longbaseline observations, we spatially resolve a massive disk down to 300 AU, and detect spiral patterns in it. Through a quantitative analysis that combines both analytical and numerical approaches, we find compelling evidence that the most likely scenario to create the spirals is through a close flyby of a nearby gas condensation. The detection of the Keplerian disk itself, combined with the flyby event caught in action, suggests that this early O-type protostar forms in a similar way to low-mass stars, subject to not only disk-mediated accretion, but also flyby-impact disk evolution.

Paper: https://arxiv.org/abs/2206.04136

Code validation and verification is - or at least should be! - part of our daily routine as astronomers. Comparing our results to those of our colleagues is both valuable and necessary. But how often do we go the extra mile and attempt to not only replicate each other's results, but also using the same tools (simulation/analysis software) to obtain them?
In this informal discussion I will present the results of a supernova radiative-transfer code-comparison initiative (StaNdaRT - this won the acronym contest) bringing together 30 researchers and 10 numerical codes, starting with how (and where) it all began and ending with the submission of our first paper one month ago... and all the excitement and drama that happened in between! An enriching scientific and human adventure that I'd like to share with you, hoping to receive feedback/advice and hear from your own similar experiences.
 

The final architecture of planetary systems depends on the extraction of angular momentum and mass-loss processes of the disks in which they form. Recently, there has been a growing recognition that magnetic outflows launched from disks (aka ’’MHD disk-winds’’) could control the extraction of angular momentum. If so, planet formation would be profoundly impacted as wind-driven accretion can enhance the growth rate of planetary cores, affect the migration pattern of forming planets, and control disk dispersal. However, the presence of MHD disk-winds remains an open question.
Now, near-complete surveys of multiple star-forming regions with ALMA and VLT provide us with an unprecedented statistical sample of stellar masses, mass accretion rates, and disk (dust) masses that can be used to test disk evolution models. In this talk, I revisit these data from the new vantage point of wind-driven accretion. The paradigmatic viscous model of Shakura-Sunyaev is extended to include MHD disk-winds (Tabone+2022a), and a synthetic disk population approach is developed to compare our model to the recent surveys of star forming regions. I will show that wind-driven accretion can naturally explain disk dispersal and the observed correlation between accretion rates and disk masses (Tabone+2022b). I will finally discuss the new avenues opened by our ALMA large program AGE-PRO that will give access to the secular evolution of disk (gas) sizes and improve our estimates of disk total masses. This work constitutes a first step toward the construction of realistic planet formation models in the emerging paradigm of MHD disk-winds.

Analysis of cosmological survey data is challenging for a host of reasons; post-CMB the fields are not gaussian random fields, and we don’t have a good handle on their statistical properties, so how can we do science?   We can make summary statistics (power spectra, correlation functions etc) and assume their distributions, or more ambitiously build a complete Bayesian hierarchical model for the data.  In this talk I will show three different BHMs for cosmology, Almanac (which characterises the statistical properties of cosmic shear data), BORG-WL (which infers cosmology and the initial conditions of the Universe), and a BHM for the redshift distribution of broad-band photometric surveys, and present a re-analysis of the KiDS 450 data with Bayesian redshift distributions.

The observed evolutionary decrease of the C-12/C-13 isotopic ratio, Li and C abundances, accompanied by the increase of the N abundance, in low-mass stars on the upper RGB is caused by extra mixing in their radiative zones. Multi-dimensional hydrodynamic simulations of thermohaline convection have demonstrated that its rate of mixing is almost two orders of magnitude as low as what is required to reproduce the observational data. Therefore, the search for an alternative mechanism of the RGB extra mixing still continues. To simultaneously explain the observed Li depletion on the lower part of the upper RGB followed by a presumed fast Li enhancement in the vicinity of the RGB tip, we consider a model of RGB extra mixing in which the diffusion coefficient strongly increases with the luminosity. With analytical prescriptions for the rates of mixing by internal gravity waves (IGWs) generated by turbulent convection in the envelopes of RGB stars, that are partly supported by our 3D hydrodynamical simulations, we can reproduce the high Li abundances recently revealed in red-clump stars. The results of our simulations also support the hypothesis that the C-13 pocket in thermally-pulsing AGB stars, necessary for the main s process to occur under radiative conditions, could be formed as a result of proton ingestion by IGW mixing.

Debris disks are young analogs of the Kuiper belt of the Solar System. Km-sized bodies collide with each other, releasing large amount of small dust grains that we can detect in near-IR scattered light observations. In this talk, I will discuss what we can learn from such observations, with a special emphasis on the properties of the small dust particles. I will also discuss some of the possible pitfalls that we need to account for when modeling these observations, namely the vertical scale height of the debris disks.

We present a new solution for the steady state distribution of stars around a supermassive black hole. This solution includes segregation of different masses and clarifies concepts of constant flux vs zero flux, which were a source of confusion in the past.

We apply this solution to (i) discuss the innermost part of our own galaxy, giving prediction to the number of stars in short period orbits (ii) show that galactic centers will be a dominant source for LISA at 10^-3 Hz, (iii) discuss a possible model for Quasi periodic eruptions from main sequence stars, that is consistent with the observed event rate.

Paper: https://arxiv.org/abs/2205.12284

G4S_2.0 is a new project funded by the Italian Space Agency which aims to perform measurements in the field of Fundamental Physics with two satellites, DORESA and MILENA, of the Galileo-FOC constellation. These satellites are characterized by the high eccentricity of their orbits and the accuracy of their atomic clocks. For these characteristics, they have recently been used to improve a previous measurement of gravitational redshift (GRS) by Gravity Probe-A in 1980 ([1]). GRS, which is a local position-invariance test, is only one of the predictions of General Relativity (GR) that can be tested with the Galileo constellation. In particular, the G4S_2.0 project aims to provide a new measurement of GRS and to measure relativistic precessions of the elliptical orbits. These results will place new constraints on possible alternative theories of gravitation, both metric and non-metric in their structure. Furthermore, constraints on the presence of Dark Matter in our Galaxy can be placed by analyzing the data of the constellation's atomic clocks. In this framework a fundamental point is obtaining a satellite orbit solution precise as far as possible. For this purpose, we focus firstly on the precise orbit determination and on a dynamic model for the non-conservative forces acting on these satellites. In particular, the model manages the perturbing effects produced by the direct solar radiation pressure (the major perturbation), the Earth’s infrared radiation and the Earth-albedo. The results of G4S_2.0 project will extend the number of tests of Einstein’s Theory of GR that can be achieved with Galileo satellites.

[1] Vessot R.F.C. et al., (1980) Test of relativistic gravitation with a spaceborne hydrogen maser. Phys Rev Lett 45(26):2081–2084. https://doi.org/10.103/Phys.Rev.Lett.45.2081.

The currently hierarchical model of the formation of the Milky Way is based on the idea that a series of accretion and merging events led to its assemble. These accretion events may leave their imprint in the form of structures such as stellar streams, shells or clouds, which appear as overdensities with respect to the underlying halo distribution. Thus, finding new overdensities idates is crucial to properly infer our galaxy's formation history.

RR Lyrae (RRL) stars have been used to find or trace the shapes of many Milky Way halo overdensities. This is because RRL are sufficiently rare to not randomly form in pairs outside of stellar structures. However, we required a kinematic analysis on RRL to relate them to the same structure.

In our work, we had been analyzing the orbits and special distribution of known overdensities and new idates. Our sample of RRL contains their 3D spatially positions, proper motions, radial velocities, and in some cases chemical composition.

In this talk, we will be sharing our kinematic analysis of this sample. We will also discuss the importance of finding new overdensities and how increasingly larger databases, such as afforded by Gaia, make it necessary to implement improved data analysis techniques in order to more proper and efficient analysis.

Finally, we will discuss the efficiency of clustering algorithms, such as DBSCAN, in the classification of new idates of stellar overdensities, by analyzing the effectiveness to recognize known overdensities, such as Virgo Overdensity.

A semi-empirical model is presented aiming at exploring the incidence of X-ray selected Active Galactic Nuclei (AGN) in massive clusters of galaxies (>3 x 10^{​​​​​​14}​​​​​​ M_{​​​​​​\odot}​​​​​​) to z~1.25 and constraining the role of small scale environment (<1 Mpc) in triggering accretion events onto supermassive black holes. Comparison of the model predictions with observations suggests differential evolution of the X-ray AGN fraction in clusters relative to the field. At low redshift, z~0.2, high density environments appear to suppress X-ray AGN with respect to the field. In contrast, at redshift z~1.25 the fraction of X-ray AGN in massive halos is enhanced relative to the field expectation, particularly in the case of high accretion luminosity events, log(L_X(2-10 keV) (erg/s)) > 44. These findings  point to a strong and redshift-dependent influence of the small-scale environment (<1 Mpc) on the growth of black holes. Our results are discussed in the context of different physical processes occurring in dense environments (e.g. ram-pressure, interactions) that could be responsible for the observed trends of the X-ray AGN fraction with environment.

We present evolutionary models for a set of massive stars, introducing a new prescription for the mass-loss rate obtained from hydrodynamical calculations in which the wind velocity profile, $\varv(r)$, and the line-acceleration, $g_\text{​​​​​​​​line}​​​​​​​​$, are obtained in a self consistently way.

We found important differences between standard and our new self-consistent tracks.

Models with the new recipe for $\dot M$ retain more mass during their evolution, which is expressed in larger radii and consequently more luminous tracks over the Hertzsprung-Russell diagram.

Later increments in the mass-loss rate for tracks when self-consistency is no longer used, attributed to the LBV stage, produce different final stellar radii and masses before the end of H-burning stage, which are analysed case to case.

Moreover, we observed remarkable differences for the evolution of the radionuclide isotope $^{​​​​​​​​26}​​​​​​​​$Al in the core and the surface of the star.

Since $\dot M_\text{​​​​​​​​sc}​​​​​​​​$ are weaker than the commonly adopted values for evolutionary tracks, self-consistent tracks predict a later modification in the abundance number of $^{​​​​​​​​26}​​​​​​​​$Al in the stellar winds.

This new behaviour could provide useful information about the real contribution of this isotope from massive stars to the Galactic interstellar medium.

Radio-Loud (RL/jetted) AGNs are among the brightest sources at all wavelengths and are usually associated with the densest regions of the Universe. Their relativistic jets can affect both the SMBH growth and the surrounding IGM and have been observed extending up to Mega-parsec scale.

After 20 years from the detection of the first extended kilo-parsec extragalactic jet in the X-rays, the mechanism responsible for their high-energy emission at these scales is still under debate.

At the same time, it was recently found that the cosmological evolution of the jetted AGN population significantly differs when observed in the X-ray or the radio band. Their X-ray space density peaks at much earlier times (z~4) when compared to their radio one (z~2), which would imply a different redshif evolution of the typical X-ray luminosities with respect to the radio ones.

In this talk I will show how the Inverse Compton interaction between the CMB photons and the electrons within relativistic jets (IC/CMB) can nicely solve both these problems. Our results are based on statistical studies performed on the largest well-defined samples available to date (up to z~5) and the detailed study of the most distant X-ray jet resolved to date (z=6.1).

Finally, I will also present our efforts to expand current samples at even higher redshift, where the effect of the CMB is stronger. By exploiting the most recent radio surveys, in less than one year we were able to discover three new RL AGNs at z>6, where only four were known before.

We present a new model for the evolution of spatially-resolved gas-phase metallicities in galaxies from first principles. We show that metallicities depend on four ratios that collectively describe the metal equilibration time-scale, production, transport, consumption, and loss. When normalized by metal diffusion, metallicity gradients are governed by the competition between radial advection, metal production, and accretion of metal-poor gas from the cosmic web.

The model naturally explains the varying gradients measured in local spirals, local dwarfs, and high-redshift star-forming galaxies. We use the model to study the cosmic evolution of gradients across redshift, showing that the gradient in Milky Way-like galaxies has steepened over time, in good agreement with both observations and simulations. Simultaneously reproducing the observed mass-metallicity and mass-metallicity gradient relations in the local Universe from the model also shows that galaxies transition from the advection-dominated to the accretion-dominated regime as they increase in mass.

The same transition also occurs in galaxies from high to low redshifts, which mirrors the transition from gravity-driven to star formation feedback-driven   turbulence. The shape of metallicity-based galaxy scaling relations is governed by the metal enrichment of outflows. Lastly, we show that the model also explains the observed relationship between metallicity gradients and galaxy kinematics at high redshift, and provides direct predictions for galactic chemical evolution that can be tested against future observations.

Feedback from Active Galactic Nuclei (AGN) is a main ingredient of cosmological simulations, as well as the possible driver of the AGN/host-galaxy coevolution. If AGN regulate the star formation (SF) of the host galaxy, they should act on the molecular gas content, that is fuel also for the SF. Nonetheless, results in the literature are controversial: local host galaxies are indistinguishable from non-active ones, while high-z AGN are usually CO depleted, yet typically selected because powerful (log(L[bol])>46) and/or as good candidates for hosting outflows. To fill this observational gap, two surveys of unbiased, high-z, X-ray-selected AGN were conceived to investigate the link between SF and AGN-driven kpc-scale ionized outflows: SUPER (z~2–2.5, logL[bol]~44.2–47.8) and KASHz (z~1–2.5, logL[bol]~43.5–46.3). The SUPER team recently found that significant CO depletion is present only in the most massive host galaxies (log(M[star]/M[sun])>11), demonstrating the importance of using unbiased samples representative of the AGN population at cosmic noon.

I will present a study on the total molecular gas content of KASHz AGN (as traced by ALMA observations of CO in Band 3 and 4), covering a wider redshift and bolometric luminosity range than the SUPER ALMA sample. I will report on how the molecular gas reservoir of KASHz sources relates to the properties of their host galaxy (stellar mass, rate of SF), as retrieved from SED fitting. By means of a control sample of non-active, PHIBBS galaxies, matched in stellar mass, rate of SF and redshift, I will show that CO depletion is not significant in KASHz AGN. I will then compare our results to those of the SUPER survey and discuss the different outcome when we also include literature high-z AGN in the analysis.

Paper: https://arxiv.org/abs/2112.08233

Star clusters with ages up to about 2 Gyr show peculiar features in their colour magnitude diagrams, such as split main sequences and extended turn-offs. These features appear to be fundamentally different from those observed in ancient globular clusters, as young star clusters lack the light-element abundance variations that are characteristic for globulars. Instead, stellar rotation has been suggested as the underlying cause, altering the colours of the stars via changes to their hydrostatic equilibria. While an observational confirmation of this idea had been lacking for many years, MUSE proved to be a game changer thanks to its unique capabilities of performing spectroscopy in crowded stellar fields. In my talk, I will present our efforts to measure the stellar rotation rates in a sample of massive star clusters in the Magellanic Clouds using MUSE. I will also discuss the implications for the formation of star clusters that arise from the presence of groups of stars with very different rotational velocities.

Stars comprising the Milky Way's stellar halo safeguard important chemo-dynamical information that enables the reconstruction of the mass assembly history of the Galaxy. Of particular importance are the halo populations in the innermost regions of the Milky Way, as they likely retain pivotal information that may help decode the early stages of the formation of the Galaxy, but however have so far been concealed due to the limitations in observing such regions due to high stellar density and dust extinction.

In this talk I will present results from two independent studies aimed at tackling two open questions in Galactic archaeology: "What is the Milky Way's mass assembly history?"; and "How much do globular clusters (GC) contribute to the total stellar halo mass budget?". First, I will provide evidence for the discovery of a new metal-poor substructure that displays chemo-dynamic signatures of accreted populations located within the heart of the Galaxy. Given the properties of this newly identified substructure (dubbed "Heracles"), we conjecture that it is the remnant of an accretion event that occurred in the early life of the Galaxy, which constituted a major building block of the Milky Way halo, and played a major role in the formation of the Milky Way. Following, I will present results on a study focused on assessing the contribution of dissolved and/or evaporated GC stars to the Galactic stellar halo. Using a density modelling procedure, I will show results that suggest there is a much higher contribution of dissolved/evaporated GC stars in the inner regions of the Galaxy when compared to the outer regions.

Stellar activity poses a severe limitation to the search and characterisation of small exoplanets with the radial velocity method. This is particularly important for M dwarfs, as they are crucial targets for both ground-based instruments (e.g., SPIRou, NIRPS, CRIRES) as well as space-based missions (e.g., JWST, ARIEL), but can manifest high activity levels over long time-scales. Efficient activity filtering techniques are therefore necessary to disentangle genuine planetary signatures and improve the detectability. In this context, and knowing from previous studies that different spectral lines are affected differently by magnetic activity, we developed a new mitigating technique based on a randomised selection of lines to use in Least-Square Deconvolution (LSD). We benchmarked the analysis on optical spectropolarimetric time series of the active M dwarf EV Lac collected with ESPaDOnS at CHFT, obtaining a reduction of the radial velocity dispersion by at least 50-60%. A similar and consistent improvement was also found when targeting stars of analogous (AD Leo) and lower (DS Leo) activity levels. Finally, we injected synthetic planets with semi-amplitudes between 60 and 120 m/s (i.e. 0.3-0.6 MJup) in our data sets containing moderate (20 m/s) and high (200 m/s) activity levels and we retrieved reasonably unaltered planetary signals, indicating that our technique does not suppress these signals substantially.

In this talk I would like to present the study of the Hydra I cluster, at z∼0.012, which is a target of the VST Early-type galaxy Survey (VEGAS). The observations of the cluster were obtained at the Very Large Survey Telescope (VST), using the Omega-CAM instrument, in the SDSS g- and r-bands.
Deep images allowed to map the galaxy structure out the regions of the stellar halos (down to mu_g~28 mag/arcsec^2), to detect the diffuse intra-cluster light components and the population of low-surface brightness (LSB) galaxies (i.e. dwarfs and ultra-diffuse galaxies).
In particular, we studied  how the LSB galaxies  are distributed in the cluster, in order to map the mass assembly of the Hydra I cluster. We discovered that galaxies are grouped in substructures in different regions of the covered cluster area. The non-uniform spatial distribution of galaxies supports the conclusions of Arnaboldi et al. (2012); Lima-Dias et al. (2021), for which several small galaxies are falling through the cluster core, feeding the cluster mass assembly process.
This study motivated a spectroscopic follow-up with MUSE@VLT, which has been approved a large program in P108. This project will be also presented in my talk.

Exoplanetary research has provided us with exciting discoveries of planets around very low-mass (VLM) stars (e.g., TRAPPIST-1 and Proxima Centauri). However, current theoretical models strive to explain planet formation in these conditions and do not predict the development of giant planets. Recent high-resolution ALMA observations of the disk around CIDA 1, a VLM star in Taurus, show substructures hinting at the presence of a massive planet. In this talk, I will present the results of our recently accepted paper, where we aim to reproduce the observed dust and gas emission of CIDA 1, assuming the structures are shaped by the interaction of the disk with a massive planet. We modeled the protoplanetary disk with a set of hydrodynamical and radiative transfer simulations, varying the mass and location of the embedded planet. Our models indicate that a planet with a minimum mass of ∼1.4 MJup orbiting at a distance of ∼10 au can explain the morphology and location of the observed dust ring. Moreover, we can reproduce the observed low dust spectral index and the morphology of the 12CO and 13CO channel maps where the cloud absorption allowed a detection. Our results suggest the presence of a massive planet orbiting CIDA 1, thus challenging our understanding of planet formation around VLM stars.

The Galactic halo is criss-crossed by long stellar streams that are probably the remnants of defunct globular clusters and dwarf galaxies. I will present the recent discoveries of these structures from Gaia mission data, and provide a lightning tour of some of the highlights.

While streams clearly inform us in a direct way about past accretions onto our Galaxy, perhaps their most promising property is that they allow us to probe the dynamics and past structure of the Milky Way. I will present our work on a novel machine learning technique to measure the local and globa acceleration field and how it changes through time.

The AAO has long and successful history in developing astronomical instruments for many of world's premier telescopes. The AAO now sits as a department of Macquarie University and is a key node of the Astralis Instrumentation Consortium. This talk will present an overview of our current programme covering a description of our hardware projects (which include multi-object and high resolution spectrographs, fibre positioning systems, adaptive optics, and photonic developments); and our software and research data projects.

Paper: https://arxiv.org/abs/2205.07916

The stellar feedback is an energetic interaction between star clusters and the surrounding interstellar medium (ISM) that self-regulates the star formation in giant molecular clouds. Studying stellar feedback generally relies on observations of star-forming regions but inferring the physical properties from photometric and spectroscopic measurements is difficult because observational data are highly degenerate due to the complexity and non-linearity of stellar feedback. In this talk, I will introduce a novel method that couples a conditional invertible neural network (cINN) with the WARPFIELD-emission predictor (WARPFIELD-EMP) to estimate the physical properties of star-forming regions from spectral observations. In our first paper (Kang et al. 2022), we presented a cINN that predicts seven physical parameters (cloud mass, star formation efficiency, etc) from the luminosity of 12 optical emission lines ranging from 3700 to 9600Å. Testing and validating our network with synthetic models that are not used for training, we confirmed that our network is a time-efficient and powerful tool that provides accurate and precise posterior distributions for each parameter. However, degeneracy sometimes remains depending on the characteristics of the object to be analyzed. Since we have to take into account observational uncertainty in analyzing the real observation data, I will present two methods of considering observation errors in using the cINN: treating the error after training or training the network together with the error.

Massive stars play crucial roles in determining the physical and chemical evolution of galaxies. They shape their environment from early in their protostellar phase when they blast the surrounding with powerful jets, up until their violent deaths in the form of supernova. However, they form deeply embedded in their parental clouds, making it challenging to directly observe these stars and immediate environments. Notwithstanding, their massive outflows can extend several parsecs and since accretion and ejection processes are intrinsically related, they can provide crucial information about the processes governing massive star formation.

In this talk, I will present the IRAS 18264-1152 high-mass star-forming complex and reveal the jets through NIR spectro-imaging. We observe the molecular hydrogen (H2) NIR jets in the K-band (1.9-2.5μm) obtained with the integral field units VLT/SINFONI and VLT/KMOS. We compare the geometry of the NIR outflows with that of the associated molecular outflow, probed by CO(2-1) emission mapped with the SMA. The spectro-imaging analysis focuses on the H2 jets, for which we derived visual extinction, temperature, column density, area, and mass. The intensity, velocity, and excitation maps based on H2 emission strongly support the existence of a protostellar cluster in this region, with at least two (but up to four) different large-scale outflows, found through the NIR and radio observations. This multi-wavelength comparison also allows us to derive a stellar density of 4000 stars pc-3 showing that relatively low number density region can harbour massive protostars. In conclusion, our study reveals the presence of several outflows driven by young sources from a forming cluster of young massive stars. Moreover, the derived stellar number density together with the geometry of the outflows suggest that massive stars can form in a relatively ordered manner in this cluster.

While numerous exoplanets have now been uncovered in stellar binaries, the impact of companion stars on planet formation and evolution is still not understood. In this talk, I will present results of population trends seen among the known sample of planets in multiple star systems, which allows us to investigate the effects of stellar binarity on the resulting planetary architectures. In particular, observations of stars hosting high-mass close-in giant planets and brown dwarfs find an excess of binary companions on few hundred AU separations, and different planet demographics for these systems, suggesting that such binaries may provide favourable conditions for the formation of the observed inner companions. I will show results from simulations of self-gravitating protoplanetary disks adapted to binary-star environments, which show that certain binary configurations may trigger gravitational fragmentation and lead to the formation of giant planets in otherwise-stable disks.

Astronomy is host to a wide variety of so called inverse problems. That is problems, where we have a fairly good understanding of how the fundamental physical properties of a system give rise to corresponding sets of observables (via e.g. simulations), but where the inverse, i.e. recovering the underlying properties of the system from the observations, is a much more difficult task and often subject to degeneracy. Invertible Neural Networks (INNs) are a deep learning approach that is particularly well suited to solving degenerate inverse problems, as they can predict full posterior distributions for the physical parameters of interest.

In this talk, I will give a short introduction to INNs and how they solve inverse problems, and introduce several applications in astronomy that our group is working on. The latter include among others the recovery of stellar physical parameters from photometric observations with the Hubble Space Telescope and the 3D density reconstruction of dust clouds based on thermal dust emission maps. 

Paper: https://arxiv.org/abs/2203.08234

Brown dwarfs (BDs) lie in the substellar mass regime, and are a bridge between stars and planets, thus providing a unique window into the unknowns of their formation processes. The dominant mechanism behind the formation of BDs is still not fully constrained. In fact, BD formation is expected to be affected by the environment in which they are born, in particular, an environment with high stellar densities and/or large number of massive stars would increase the efficiency of BD production compared to stars. In order to test these hypotheses, we are studying the low-mass population of three massive young clusters with extreme environmental properties compared with nearby star-forming regions. One of these clusters is NGC 2244 (d=1.5 kpc), which hosts a large number of OB stars and presents a low stellar density. We have built a robust sample of cluster members using deep photometry, astrometry and multi-object spectroscopy (VIMOS and KMOS/VLT), resulting in the first spectroscopically confirmed BDs beyond 1 kpc. In this talk, I will present our newly developed method for spectroscopic analysis of cool dwarf spectra in the NIR, implementing machine learning models to efficiently separate young members from field contaminants, that will be of special interest for upcoming multi-object facilities such as NIRSPEC and NIRISS/JWST and MOONS/VLT. Furthermore, I will present our results on the BD population in NGC 2244 and compare them with the other massive clusters in our sample, as well as with nearby star-forming regions.

The Galactic Center harbors a peculiar population of young stars some distributed in a clockwise rotating disk. In this talk I will present the largest spectroscopic survey of the Nuclear Star Cluster using over 600 hours of ESO's SINFONI instrument. The observations were carried out over the last two decades and now cover roughly 25 arc-seconds squared of the Galactic Center. This is a substantial increase in coverage compared to previous works. The analysis of the spectra has led to the spectroscopic classification of over 2800 stars.

We identified around 90 new young stars increasing the total number of known young stars by almost a factor two to ~200. Furthermore, I will show that these young stars are not isotropically distributed, but instead reside in a system consisting of a central warped clockwise disk and several streamers/ streams of young stars at larger radii. Lastly, I will discuss the implications of this result for star formation in the Galactic Center, where I will argue that the young stars formed after the collision and subsequent accretion of two giant molecular clouds about 6 mega years ago.

Cosmological simulations represent excellent tools to study the formation and evolution of structures in the Universe.
In recent years, improved numerical methods, increased computing power and a better understanding of physical processes have made it possible to reproduce many astrophysical observables at different scales. In this regard, clusters yield a special position: being the largest gravitationally bound systems in the Universe and having formed at late times, they are expected to still retain traces of the main mechanisms involved in structure formation. I will revise the dynamical properties of the cluster's central regions, specifically of the brightest cluster galaxies (BCGs) and the surrounding diffuse intracluster light, addressing the connection with their host cluster. I will highlight the support that simulations can provide to interpret several aspects and systematics included in observations which cannot be disentangled otherwise, such as the expected contribution of intracluster light in these measurements. At last, I will revise future and ongoing projects.

The past few years have seen at least six major new radio telescopes come into operation around the world. They incorporate new technologies and processing techniques that have enabled revolutionary advances in sensitivity, frequency coverage and field of view. I will provide an update from one of these telescopes - ASKAP, a wide-field radio telescope operating in a remote region of Western Australia. The main focus of the talk will be on recent science results from ASKAP in two areas: 21cm neutral hydrogen (HI) absorption in galaxies at intermediate redshift; and Fast Radio Bursts (FRBs) and their host galaxies. I will also mention some of the optical follow-up studies being carried out with ESO telescopes, as well as describing the recently-completed Rapid ASKAP Continuum Survey (RACS) which provides a new resource for a wide range of multi-wavelength studies.

Paper: https://arxiv.org/abs/2203.08234

The huge improvements in the precision of the published data in Gaia EDR3, particularly for parallaxes and proper motions, has given a push to the detection of new open clusters in the Milky Way. In this talk, I will revise our methodology to search for open clusters, and how it has been adapted to a Big Data environment to analyse hundreds of millions of stars looking for relations and patterns among them. The application of the method to Gaia EDR3 has resulted in the discovery of 664 new open clusters, which, added to the 646 found in our previous searches in Gaia DR2, represent about 50% of the known open cluster population. I will also revise how this updated open cluster catalogue, with estimated astrophysical parameters, can provide insights about the structure and evolution of our Galaxy, particularly focusing on the spiral arms.

The Magellanic clouds are a great training ground to understand galaxy interactions and formation within the local group. Many models try to explain their origin and interactions with one another and the Milky Way. Unfortunately, due to significant uncertainties in measurements, many parameters of these models are only loosely constrained. However, these limitations are currently changing. Large scale surveys such as Gaia and VMC enable new methods to study the kinematics of this pair. The proximity of the Large and Small Magellanic Cloud (LMC and SMC) provides a unique opportunity to explore the kinematics of resolved stellar populations within an interacting pair of galaxies with exceptional resolution. Their past interactions created many tidal features, such as the Magellanic Bridge and Stream, distributed across vast regions in the sky and containing several star populations. The kinematics of those individual populations can provide insight into the past of the Clouds.

We developed a new method to distinguish between Magellanic and Milky Way stars based on a machine-learning algorithm combining VMC, Gaia, and the latest StarHorse distance estimates. This approach increases the number of Magellanic sources compared to previous studies. As a result, we can now study the kinematics of stellar populations in more detail. Our results show clear implications for future modelling of the Clouds. Our residual proper motions show a stretching on the northern and north-eastern sides, which could be due to the influence of the Milky Way. While the residuals in the southern region implicate a connection with the impact of SMC at the most recent interaction between the LMC a few hundred million years ago, agreeing with newer model predictions. Our approach also enables a search of Magellanic sources connected to the stellar component of the Magellanic Stream, with location, extents and kinematics that are still less studied than the gaseous component.

Stars are fossils that retain the history of their host galaxies. Elements heavier than helium are created inside stars and are ejected when they die. Elements heavier than iron (such as gold) are also produced by neutron star mergers. From the spatial distribution of elements in galaxies, it is therefore possible to constrain star formation and chemical enrichment histories of the galaxies. This approach, Galactic Archaeology, has been popularly used for our Milky Way Galaxy with a vast amount of data from Gaia and multi-object spectrographs. This approach can also be applied to external galaxies thanks to integral field spectrographs. Theoretical predictions are also available including incorporating detailed chemical enrichment in hydrodynamical simulations from cosmological initial conditions. At all redshifts (z<5) massive galaxies are more metal-rich than low-mass galaxies following the mass-metallicity relations, and the central parts of galaxies are more metal-rich than the outskirts producing metallicity radial gradients. These predictions will be compared and tested with recent and future observations such as with ALMA and JWST.

The characterization of large-scale gas-circulation processes in the cosmological environment of galaxies is of fundamental importance to understand galaxy evolution and cosmological structure formation. The Local Group represents an important test bench to investigate these processes with very high accuracy and spatial resolution based on large observational data sets. In this talk, I will review the various gas components in the circumgalactic media of MW and M31 and in the LG intragroup medium and discuss their chemical composition, kinematics, and mass-flow rates in the context of the on-going formation of the MW and Local Group. Recent results from our observational surveys with HST and constrained cosmological MHD simulations will be presented.

Cool giant and supergiant stars are among the largest and most luminous stars in the Universe and, therefore, dominate the integrated light of their host galaxies. These stars were extensively studied during last few decades, however their relevant properties like photometric variability and mass loss are still poorly constrained. Understanding of these properties is crucial in the context of a broad range of astrophysical questions including chemical enrichment of the Universe, supernova progenitors, and the extragalactic distance scale.

The atmospheres of evolved stars are characterized by complex dynamics due to different interacting processes, such as convection, pulsation, formation of molecules and dust, and the development of mass loss. These dynamical processes impact the formation of spectral lines producing their asymmetries and Doppler shifts. Thus, by studying the line-profile variations on spatial and temporal scales it is possible to reconstruct atmospheric motions in stars and link them to the photometric variability and mass loss. The tomographic method, which is based on the cross-sectioning through the stellar atmosphere and recovering the velocity field for each atmospheric slice, is an ideal technique for this purpose.

In this colloquium, I will present the tomographic method and its application to spectroscopic and spectro-interferometric observations of giant and supergiant stars as well as to state-of-the-art three-dimensional numerical simulations to constrain their atmospheric motions on spatial and temporal scales and better understand respective mechanisms responsible for their photometric variability and mass loss.

Majority of classical Cepheids are binary stars, yet the contribution of companions' light to the total brightness of the system has been assumed negligible and lacked thorough, quantitative evaluation. I present an extensive study of synthetic populations of binary Cepheids, that aims to characterize Cepheids' companions (e.g. masses, evolutionary and spectral types), quantify their contribution to the brightness and color of Cepheid binaries, and assess the relevance of input parameters on the results. Synthetic populations are free from the selection and completeness biases, while the percentage of Cepheid binaries is controlled by the binarity parameter. With this tool I successfully reproduce recent theoretical and empirical results: the percentage of binary Cepheids with main sequence (MS) companions, the contrast-mass ratio relation for binary Cepheids with MS companions, the manifestation of binary Cepheids with evolved, giant companions as outlier data points above the period-luminosity relation. Next, I use the synthetic populations to estimate, for the first time, the percentage of binary Cepheids in the Large Magellanic Cloud, and quantify the effect of binarity on the slope and zero point of multiband period-luminosity relations. Finally, I present a promising method of detecting binary Cepheids on color-color diagrams, provided multi-epoch, high quality, multi-band data. Large volumes of such data are anticipated from Vera C. Rubin Observatory, presenting an exciting opportunity for discovery of binary Cepheids on a large-scale.

It is well known that early-type (elliptical and lenticular) galaxies are more common in denser environments. This morphology-density relation implies environment plays a significant role in the formation of early-type galaxies and the transformation between morphological types. However, the physical processes that lead to the relation are still debated. To address this question we use Convolutional Neural Networks, trained on real galaxies, to perform `visual' classification of galaxies in the EAGLE simulation. I will discuss how modern hydrodynamical simulations can reproduce the galaxy morphology-density relation and offer insights into its origin.

The accretion rate-disk mass relationship connects the evolution of the innermost disk to the outer disk mass reservoir. This relationship has long been predicted and recently has been seen observationally. However, most observational efforts have been biased towards T Tauri stars, which have benefitted from complete ALMA surveys of entire star-forming regions. On the other hand, the more massive Herbig Ae/Be stars have lacked the extensive (sub-)millimeter observations needed to determine the disk masses. In this talk I will present the accretion rate-disk mass relationship for a sample of Herbig Ae/Be stars, highlighting how these objects differ from their lower-mass counterparts and what may be driving those differences. I will also discuss a bias in the Herbig sample and how that limits our understanding of late-stage disk evolution around these objects.

Scenarios of structure formation with axion-like particle dark matter can have distinctive signatures on scales ranging from kiloparsecs to astronomical units. They are governed almost entirely by the particle mass and therefore very predictive. However, much of the phenomenology is highly nonlinear, requiring large simulations and, in some cases, novel computational tools. Very similar phenomena might have appeared in an early matter dominated epoch after inflation. Here, the inflaton field itself fragments gravitationally, forming structures on microscopic scales that closely resemble cosmological large-scale structure.

The Fornax galaxy cluster provides an unparalleled opportunity of investigating galaxy formation and evolution in a dense environment in great detail. Although the Fornax cluster seems relaxed, various studies have shown that the Fornax cluster still is accreting various sub-groups. Previous photometric studies of the central massive galaxy NGC1399 revealed an excess of globular clusters (GCs), suggesting accretion of GCs from nearby, interacting major galaxies like NGC 1404.

To kinematically characterize the Fornax cluster's intra-cluster population and understand the assembly of the outer halos of cluster galaxies, we have analyzed the VLT/VIMOS spectroscopic survey of the Fornax cluster covering half of the cluster virial radius (~300 kpc). Combined with previous spectroscopic measurements, this leads to the most extensive catalogue of radial velocity measurements with a total of 2341 confirmed GCs in Fornax.

Our analysis of this unprecedented dataset provides the kinematical characterization of the Fornax cluster's intra-cluster component. We found that metal-rich GCs are concentrated around the major galaxies, while metal-poor GCs are kinematically irregular and extensively spread throughout the cluster's core region. About 30% of the GCs contribute to the intracluster population. With the final goal to understand the mass assembly of the Fornax cluster and its member galaxies, in this talk, I will present the kinematics of GCs in the core of the cluster, and ongoing dynamical mass-modelling results obtained from this dataset. I will discuss possible kinematical interaction signatures between NGC1399 and the major galaxies of the Fornax cluster.

Dust is integral to the physics of galaxy evolution and impact the observed SEDs. I present a framework to investigate dust properties combining physics relevant to dust evolution with hydrodynamic simulations. In this model, dust grains form in stellar ejecta and are processed in the ISM via grain growth, grain-grain collisional processes, and destructive processes. Utilizing large-volume cosmological simulations, I present the scaling relations between dust-to-gas ratio with other galaxy properties, and show the evolution grain size distributions with a focus on Milky-Way mass galaxies. I discuss physical processes driving the evolution of dust properties and their impact on extinction features. Additionally, I show results from isolated galaxy simulations with an explicit ISM and feedback model SMUGGLE, and discuss the cause of different types (e.g. Milky-Way type, or SMC-bar type) of extinction laws.

Rationale

The formation of bulges is still one of the most debated problems of galaxy evolution. Understanding their formation and evolution, and their interplay with other galaxy structural components provides crucial information on the formation history of galaxies at large. So far, the problem of bulge formation has been addressed following three main strategies, by looking at:  (i) high redshifts, when such structures are still forming; (ii) the local Universe, where a variety of bulges with different properties can be observed; and (iii) the Milky Way, which offers the unique opportunity to study in detail the closest bulge and the properties of its resolved stellar populations. In parallel, extensive theoretical work has been carried out with hydrodynamic simulations of isolated galaxies, idealised mergers, and galaxy formation in the cosmological context, providing a framework for interpreting these observations. Although very different in terms of techniques and diagnostics, these fields of research are very much complementary in the broad framework of the formation and evolution of the central regions of galaxies.

Central stellar concentrations akin to bulges are observed in massive galaxies already at z ~ 2, with star formation in the centre almost over but continuing in the surrounding discs. The formation of giant clumps in high-z discs through violent instability and their migration and coalescence to the centre has been proposed as a possible scenario for the formation of bulges. Alternatively, gas-rich mergers can lead to the central pile-up of star-forming gas with short depletion time. The properties of discs at high z are however quite different from those observed in the nearby Universe, with high-z discs being more turbulent and with higher gas fractions.

Studies based on galaxies in the local Universe have established that the central structures in disc galaxies can display a variety of properties. On the one hand, some galaxies contain so-called classical bulges, which are dispersion-dominated structures, with old and alpha-enhanced stellar populations, thought to have formed through violent processes, at early times and on short timescales. On the other hand, internal phenomena such as bar-driven secular processes produce different components, such as the boxy/peanut-shaped bulges (buckled bars) which exhibit cylindrical rotation, and age and chemistry signatures characteristic of the disc. Furthermore, bar-driven gas inflow to the central regions build rotation-dominated structures, often referred to as nuclear discs and nuclear rings.

Recent surveys have confirmed the boxy/peanut-shape structure of the Milky Way bulge, supporting the bar-buckling scenario. In addition, our bulge rotates cylindrically and the metallicity and kinematics of its stellar populations are well reproduced by simulations with bar-driven secular evolution of thin and thick discs. However, the distribution of stellar ages in the MW bulge is still highly debated, and therefore there is still no general consensus on the mechanisms responsible for its formation.

The goal of this workshop is to bring together the galactic, extragalactic, and high-redshift communities, both theorists and observers, with the final goal of fostering fruitful discussions and new collaborations on the formation of the central regions of galaxies. Amongst the main topics to be discussed are:

+ Chemo-dynamical properties of the MW bulge

+ Observed properties of bulges and link to formation scenarios

+ Bulges in a cosmological context

+ Clumpy discs, mergers and bulge formation at high redshifts

+ Formation and evolution of bulges from a theoretical perspective

The meeting is intended to be highly participative, with substantial time devoted to discussions to promote cross-disciplinary interactions and exchange of ideas.

This ESO Workshop should set the basis for the study of galaxy bulges in the new decade.

The conference is planned as an in-person meeting. However, should you not be able to travel, we plan to accommodate on-line attendance to a limited number of participants.

For information please contact bulges2022@eso.org. If you want to receive future information on the workshop, please fill in the registration form.

Cool cores occur in half of all clusters of galaxies, centred on the most massive galaxies known. The temperature of the intracluster gas drops inward as does the radiative cooling time, to well below a Gyr. Radio jets from the central AGN blow bubbles which can heat the gas and may prevent strong cooling.  There is however much cold gas near the centre of most cool cores which can hide the presence of cooling in soft X-rays. Here I show that significant hidden cooling flows may be occurring in a small sample consisting of the Centaurus, Perseus and A1835 clusters. This has consequences for the total mass and life cycle of the cold gas as well as for the rest of these highly multiphase regions.

Topic: Using MPCDF services

For details and registration please visit:

https://www.mpcdf.mpg.de/about-mpcdf/news-events/mpcdf-introductory-user-course

An important fraction of quasars are red at optical wavelengths, indicating (in the vast majority of cases) that the accretion disc is obscured by a column of dust which extinguishes the shorter-wavelength blue emission. In recent work by our group, we have shown fundamental differences in the radio properties of SDSS optically selected red quasars, which cannot be explained with a simple viewing angle hypothesis (Klindt et al. 2019, Fawcett et al. 2020, Rosario et al. 2020, Rosario et al. 2021). In our latest work, we use VLT/X-shooter spectroscopy of a sample of red and typical quasars to gain insight into  these differences. We confirm that dust reddening is the main cause of the red colours and explore the emission line properties of our sample. We confront our spectra against accretion disc models and confirm that red quasars are powered by standard thin-disc accretion, finding tentative evidence that red quasars have higher Eddington ratios for any given black hole mass. These results suggest that dusty winds could be driving the fundamental differences in red quasars, and so they may represent an important phase in galaxy evolution. Using DESI spectra, we can now push to more extinguished, lower luminosity systems, which will test whether these results extend to more extreme reddened systems.

One of the exciting results of the last years concerning the study of the large-scale structure is the discovery of long (3-5 Mpc) bridges of radio emission connecting pairs of interacting clusters. This is the first direct evidence of the existence of particle acceleration and magnetic field amplification mechanisms outside galaxy clusters. Non-thermal components spread over such vast extents probe the dynamics of large-scale structures and the mechanisms of energy dissipation therein. In my talk, I will discuss recent results on radio bridges, showing how their observation represents a step forward in the search of the radio signature of the magnetized cosmic web.

Constraining the high redshift galaxy ISM properties provide crucial input for models of galaxy formation and evolution, and regarding the feedback processes that regulate galaxy growth. Recent ALMA measurements have revealed bright [O III] 88 micron line emission from galaxies during the Epoch of Reionization at redshifts as large as z ∼ 13. We introduce an analytic model to help interpret these and other upcoming [O III] 88 micron measurements. We cross-check our model by comparing it with detailed CLOUDY calculations, and find that it works to better than 15 per cent accuracy across a broad range of parameter space. Applying our model to existing ALMA data at z ∼ 6–9, we find the [O III] 88 µm line observations leave a degeneracy between the gas density and metallicity in these systems. We derive lower bounds on the gas metallicity and upper bounds on the gas density in the H II regions of these galaxies. These limits vary considerably from galaxy to galaxy, with the tightest bounds indicating Z>=0.5Z_solar and nH <= 50 cm^−3 at 2 − σ confidence. We quantify the prospects for breaking this degeneracy using future ALMA observations of the [O III] 52 µm line. We show that either successful detections of the 52 µm line, or reliable upper limits, will lead to significantly tighter constraints on ISM parameters. The forecasted improvements are as large as ∼ 3 dex in gas density and ∼ 1 dex in metallicity for some regions of parameter space.

Accretion is a fundamentally important process for pre-main-sequence stars, affecting disk stability and evolution, stellar rotation and activity, and planet formation and migration. The main observational challenge is probing the sub-au scales of the innermost disk, which is not always possible via interferometry. Such young stars, however, possess a wealth of high-energy emission lines, revealing the nature of accretion-related processes.

We have developed the Python package STAR-MELT to automatically extract, identify, and fit emission lines, directly from the input data. These lines can then be used to investigate the magnetospheric accretion and its temporal variability; allowing us to tomographically map the accretion structures and inner disk of the PMS stars. This is also useful for disentangling the radial velocity signatures of planets from the stellar activity and/or accretion.

STAR-MELT is now available to the community. I will present an overview of the package features, along with results from our recently published paper that features analysis of three YSOs. We find that even with similar stellar parameters, the accretion processes can be vastly different in terms of stability and nature; which has significant implications for both the formation and detection of exoplanets.

We experience a golden era in testing and exploring relativistic gravity. Whether it is results from gravitational wave detectors, satellite or lab experiments, radio astronomy plays an important complementary role. Here one can mention the cosmic microwave background, black hole imaging and, obviously, binary pulsars. This talk will provide an overview how these methods relate to each other, and will in particular focus on new results from the study of binary pulsars, where we can test the behaviour of strongly self-gravitating bodies with unrivalled precision. The talk will also give a brief update on nHz gravitational wave detection with Pulsar Timing Arrays and an outlook of what we can expect from new experiments, such as MeerKAT or the SKA.

Quasi-Periodic Eruptions (QPEs) are high-amplitude bursts of X-ray radiation recurring every few hours and provide a new channel to study how massive black holes are activated in low-mass galaxies. Previously, only two such sources were known, classified as hosting an actively accreting black hole. I will present the detection of QPEs in two further galaxies, obtained with a blind and systematic search during the first year of operations of the eROSITA X-ray telescope (Arcodia et al., Nature 2021). The optical spectra of these galaxies show no signature of black hole activity, indicating that a pre-existing accretion flow typical of active nuclei is not required to trigger these events. I will give a state-of-the-art overview of QPEs' multi-wavelength observational properties and possible origin scenarios. What we currently suggest is that QPEs might be driven by the presence of one (or more) orbiting body (-ies) with stellar mass. This could make QPEs a viable idate for the electromagnetic counterparts of the so-called extreme mass-ratio inspirals, with considerable implications for the future of multi-messenger astrophysics and cosmology.

The formation of high-mass stars has seen some significant progress over the past years. Still, being deeply embedded in their natal envelope, a definitive observational sequence for their formation is yet to be obtained. Most main sequence massive stars (~70%) belong to short-period binaries, a fact that does not reflect the binary parameters measured among populations of newly born massive stars. To bridge the gap between these two regimes, we need to obtain strong constrains on the origin of the pairing mechanism and the birth orbital properties. Different scenarios have been proposed to produce close binaries, such as the migration, in which massive binaries are originally formed at large separations and then harden on a time-scale of ~2 Myr. A strong test for this scenario is the presence of a significant number of relatively massive companions at separations corresponding to the expected size of the accretion disk. Being one of the youngest cluster in our Galaxy, M17 is an unprecedented laboratory where (proto)binaries can be caught during or immediately after their formation phase. In my talk, I will describe how optical interferometry (GRAVITY) and high-angular resolution techniques (NACO) are of great importance in characterizing multiplicity at birth. From the interferometric model fitting of visibility amplitudes and closure phases, I will present some of my latest exciting results, including two important concepts: the multiplicity and companion fraction. These results will be compared to other recent studies. Finally, I will discuss the connection with the current star formation theories and how the advent of future VLTI instrumentation will bring another piece to the puzzle.

Great progress is being made with ground-based millimeter wavelength surveys. We highlight some recent results from the Atacama Cosmology Telescope (ACT), which has been conducting large area surveys (up to half sky) since 2014. Measurements of the Cosmic Microwave Background (CMB) temperature and polarization power spectra provide constraints on the Hubble constant that are consistent with Planck satellite measurements, and evidence for tension between CMB and late-Universe constraints on the Hubble constant (Choi et al. 2020, Aiola et al. 2020). Future ACT results including more data are expected to improve on Hubble constant uncertainties from Planck for the first time. Intriguingly, fitting models of early dark energy (EDE) to Planck data do not find evidence for EDE, while fits to the ACT power spectra provide modest support (~3 sigma) for EDE compared to the Lambda-CDM cosmological model (Hill et al. 2022). The half sky ACT survey is also leading to exciting results related to stellar transients (Naess et al. 2021) and the detection of the largest catalog of Sunyaev-Zeldovich (SZ) galaxy clusters (>4000 optically confirmed) yet. We review these results and briefly describe future prospects with ACT data and the upcoming CCAT-prime and Simons Observatory surveys.

The low column density atomic hydrogen (HI) needs to be observationally traced in order to fully understand the accretion of gas onto galaxies, and the evolution of galaxies in general. And ideally this gas needs to be traced at ~kpc resolutions. Pushing the observed HI column density limit down has demanded considerable investment of time on existing radio interferometers, but with the Square Kilometre Array (SKA) Precursors coming online, we can soon expect to have a large samples of galaxies observed with high spatial resolution down to very low column densities. I would like to discuss how 'low' a HI column density can be realistically observed by these Precursors and the SKA in future, and what science we can expect from such observations. I will introduce the two relevant SKA Precursors, the relevant deep HI surveys on them, and hopefully also discuss some of the exciting new observations these surveys are starting to produce.

In this talk, I will address one of the most important questions in the field of planet formation: how millimeter- and centimeter-sized dust particles overcome radial drift and fragmentation barriers to form kilometer-sized planetesimals. ALMA observations of protoplanetary disks, in particular transition disks or disks with clear signs of substructures, can provide new constraints on theories of grain growth and planetesimal formation. I will present ALMA band 4 (2.1 mm) observations of the transition disk system Sz 91, along with previously obtained band 6 (1.3 mm) and band 7 (0.9 mm) observations. Sz 91, with its well-defined millimeter ring, more extended gas disk, and evidence of smaller dust particles close to the star, constitutes a clear case of dust filtering and the accumulation of millimeter-sized particles in a gas pressure bump. I will present the results of the spectral index (nearly constant at ∼3.34), optical depth (marginally optically thick), and maximum grain size (∼0.61 mm) in the dust ring from the multi-wavelength ALMA observations and compare them with recently published simulations of grain growth in disk substructures. Our observational results are in strong agreement with the predictions of models for grain growth in dust rings that include fragmentation and planetesimal formation through streaming instability.

A cosmological-model independent reconstruction of the expansion history of the Universe can help to shed light on the dark sector and the current cosmological tensions. I will discuss past, present, and future efforts to constrain the Hubble parameter H(z) using two optimal astrophysical probes: cosmic chronometers and gravitational waves. The differential aging of massive and passive galaxies can be used to obtain direct measurements of the Hubble parameter without any cosmological assumptions. However, robust dt estimates require deep spectroscopy to break internal degeneracies between stellar population parameters (e.g., age and chemical content). I present a recent analysis of  the stellar ages, [Z/H], and [α/Fe] of 140 cosmic chronometers at z~0.7 from the LEGA-C survey using an optimized set of Lick indices (arXiv:2106.14894). From the age-z relation of this population, a new measurement of H(z) is derived, assessing in detail its robustness and dependence on systematic effects (arXiv:2110.04304). Finally, I will discuss the prospects for gravitational wave cosmology in the context of future surveys and third-generation detectors.

I will present an overview of the Quasar Feedback Survey (QFeedS) and will illustrate its powerful capabilities to establish the role of rapidly growing supermassive black holes (i.e., quasars) in galaxy evolution. Using spatially-resolved ionized gas and stellar kinematic measurements from MUSE data, molecular gas kinematics from ALMA data, and high-quality imaging from the VLA, we are measuring in exquisite detail how z<0.2 quasars interact with the host galaxy’s interstellar medium (ISM). By combining these data, we can infer the feedback effects on the host galaxy: 1) there are clear signatures of the impact of radio jet-ISM interactions in both the ionized and molecular phases; 2) we observe outflowing, dense turbulent gas, perpendicular to the jet axis, extending to galactic scales; 3) we observe evidence for jet-induced feedback on the stellar properties. Recent simulations of jet-ISM interactions, qualitatively agree with our observations; specifically, as inclined, low power jets move through the galaxy, they strongly interact with the ISM, causing highly turbulent material to be stripped, which then escapes above and below the galaxy disk. The overall impact is to both remove gas from the host galaxy (globally suppressing star formation) and to compress the gas (locally inducing star formation). Through my analysis, I present a discussion of how such jet-induced feedback could be an important, previously underappreciated, feedback mechanism for bolometrically luminous 'radio quiet' quasars.

We recently reported the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (T ~ 270 days), high-magnification microlensing event MOA-11-191/OGLE-11-461, in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of six years, reveals a clear relativistic astrometric deflection of the background star's apparent position. Ground-based photometry is used to derive the parallax, and VLT spectroscopy is used to characterize the source. Combining the photometric, astrometric, and spectroscopic measurements, we obtain a lens mass of 7.1 +/- 1.3 solar mass and a distance of 1.58 +/- 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic-disk stars at similar distances by an amount corresponding to a transverse space velocity of ~45 km/s, suggesting that the BH received a natal "kick'' from its supernova explosion. Our mass measurement is the first ever for an isolated stellar-mass BH using any technique.

New planetary systems are made from dust and gas in the rotating disks around young stars. High-resolution observations of these planet-forming disks with the Atacama Large Millimeter Array (ALMA) can be used to learn about the planet-formation process. In particular, ALMA can trace the composition of the gas available to be accreted by planets. In this talk, I will show recent molecular line observations towards two well-studied warm planet-forming disks: HD100546 and IRS48. These disks show evidence for ongoing planetformation due to the presence of rings and asymmetries in the millimetre dust disk. The molecular emissions are linked to these dust structures. These data include first detections of the molecules NO, SO2 and CH3OCH3 in protoplanetary disks. This rich observable chemistry is due to ice sublimation and the link between the molecules and the dust structures shows that these dust traps are also ice traps. The array of detected molecules can be used to learn about the physical and chemical conditions in the disk experienced by forming planets. We determine the elemental C/O ratio in the disk using the simple molecules (SO, CS etc), and this provides a direct connection to the observed exoplanet population. On the other hand, the more complex molecules (CH3OH, CH3OCH3, etc.) shed light on the importance of inheritance from earlier stages of the star formation process. The detection of these complex and potentially prebiotic molecules in planet-forming disks provides links to how life originated in our solar system. 

Most exoplanet surveys have so far focused on stars not larger than the Sun, and about 90% of the 4500 known exoplanets lie closer to their stars than the Earth is to the Sun. This strong observational bias has recently started being complemented by direct imaging, a technique that -contrary to transits and radial velocities- is preferentially sensitive to young giant planets in wide orbits. Although giant planets have been shown to be increasingly common around more massive star, the occurrence frequency, according to radial velocity studies, has a turnover at about 2 M_sun and goes down to zero at M>3 M_sun. This is in line with theoretical expectations from the core accretion model: due to a more rapid dispersal of the protoplanetary disk around heavier stars, giant planets around intermediate and massive stars should simply not exist. To clarify if this shortage is real or if it is rather the result of an observational bias, we initiated the direct-imaging B-star Exoplanet Abundance Study (BEAST), the first survey explicitly targeting 85 young B stars (M>2.4 M_sun) to look for exoplanets around them. While the survey is still in progress, its provisional results -that I will show here- are already intriguing, challenging everything we used to know about giant planet formation under exotic environments.

The pronounced horizontal metallicity gradient along the Milky Way’s bar suggests that the inner Milky Way has a complex formation history. In this talk, I present mean metallicity, age, and orbital maps of the inner Milky Way built using the orbits of ~30,000 APOGEE Dr16 stars with Gaia kinematics integrated in a state-of-the-art bar-bulge Milky Way potential with a slow pattern speed. These maps reveal that the Galactic bar gradually transitions into a stellar inner ring. This ring is radially thick, vertically thin, and elongated along the bar’s major axis. I will explain how the presence of the inner ring, which is on average solar in metallicity and roughly 6 Gyr in age, explains the steepness of the bar’s horizontal metallicity gradient as well as how we can use the ring to give a rough estimate of the bar’s age.

The CHaracterising ExOPlanet Satellite (CHEOPS) was selected in 2012 as the first small mission (S-mission) in the ESA Science Programme and successfully launched within schedule and budget on December 18, 2020 on a Soyouz-Fregat rocket from Kourou, French Guyana. CHEOPS is the first mission dedicated to search for exoplanet transits by means of ultrahigh precision photometry on bright stars already known to host planets. The follow-up of planets with a higher precision photometry improves the measurements of the planet properties such as radii, masses (via TTVs), even shapes, and allows for defining precise transit ephemeris especially for small bodies. It also often leads to a refinement of the overall architecture of the systems (e.g. discovery of new planets). By the same token, the measuring of occultations and phase curves with a precision of only a few parts-per-million has opened a new window on the study of the atmospheres of hot planets. Being agile and able to look at a large fraction of the sky, CHEOPS offers a unique interface between the discovery (e.g. TESS) of exoplanets and their further spectroscopic characterisation by large space- (e.g. JWST & ARIEL) or ground-based (e.g. VLT & ELTs) facilities.

In the search of a sample of metal-poor bright giant stars using Strömgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, with masses between 2.5 and 6 solar masses. Ten of these stars also rotate rapidly (vsini > 10 km/s). The high stellar masses imply that these stars were of spectral type A to B when on the main sequence. This evolutionary stage is not very well characterised by observations so far, because of the short time spent by stars in this phase. This sample of giant stars allows us a close look at this rapid evolution. It is an opportunity for testing the predictions of theoretical stellar tracks on the evolution of chemical abundances and rotational velocities. We determined chemical abundances of 16 elements (C, N, O, Mg, Al, Ca, Fe, Sr, Y, Ba, La, Ce, Pr, Nd, Sm, and Eu) and rotational velocities of the stars. The chemical analysis shows that all but one of the sample stars have low [C/Fe] and high [N/Fe] ratios together with constant [(C+N+O)/Fe], suggesting that they have undergone CNO processing and mixing. The stars do not show any chemical peculiarities, except for the Ba abundance; the majority of the stars in the sample show a Ba abundance higher than solar, but solar s-process elemental abundances. The observed rotational velocities are in line with theoretical predictions of the evolution of rotating stars.

Luminous Blue Variables represent a very short stage in the life of some massive stars, characterized by significant variability, dense and steady winds, and occasional mass eruptions that rip off the outer stellar layers. By virtue of these processes, LBVs are often surrounded by large and heterogeneous circumstellar structures, like the remarkable Homunculus Nebula around Eta Car, that contain the evolutionary footprint of the parent star.

Therefore, these nebulae have been comprehensively studied at optical, infrared and radio wavelengths, resulting in a very accurate portrait of their dust and ionized gas content. However, a crucial piece of the puzzle is missing: a possible molecular counterpart. Such a component was overlooked for decades, but now we know that, under certain conditions, molecules can thrive in the hostile outskirts of LBV stars, despite the hot temperatures and
strong UV fields. By investigating this molecular component at (sub)millimeter wavelengths, we can complete the mass-loss record of these challenging sources, learning about the mechanisms behind the eruptions and disclosing their chemical peculiarities.

This talk will present the most remarkable findings of a search for molecular gas associated with Galactic LBV stars, focusing on a series of previously undetected warm molecular rings. These structures, displaying unmistakable signs of CNO-processed material, suggest an evolutionary connection that extends beyond the LBV phase. We will discuss the origin of these structures and the role of LBVs as molecular polluters, shedding light on how the most massive stars contributed to the chemical enrichment of the early Universe.

The baryon cycle is a vital ingredient to galaxy evolution models. It describes how atomic gas in galaxies cools, becomes molecular, forms stars and is exchanged with the environment via outflows. The details of the underlying processes (refuelling, outflows, metal transport, etc.), however, are not well constrained, yet. The key information lies in the circumgalactic medium (CGM), a diffuse, low surface brightness gas phase at the interface between galaxies and the intergalactic medium. The CGM can be efficiently studied from absorption features in unrelated background quasars that act as a cosmic beacon.

We advance this emerging field by studying the baryon cycle within absorption-selected galaxies. We combine observations of the ionised gas and stars (with VLT/MUSE) with those of the molecular gas - the direct fuel for star formation (using ALMA) to study the relation between the absorbing gas and the host galaxy. This combination allows us to study the complete baryon cycle. We discover a more complex structure than a one-to-one correlation between absorber and host from both optical IFU observations and ALMA observations of the molecular gas. We characterise for the first time the molecular gas excitation conditions. With our holistic approach to trace the entire baryon cycle we shed new light on these most important processes shaping galaxy evolution.

Surveys at millimeter wavelengths of protoplanetary disk populations in nearby star-forming regions have allowed us to form an empirical framework for how their dust component evolves in the first few million years of a star's existence. However, the intrinsically small sample sizes and relatively small range of irradiation regimes available make it difficult to study how and why disk properties vary across and between star-forming clouds, as a function of time and environment.

SODA (the Survey of Orion Disks with ALMA) attempts to address these problems with an unbiased uniform survey of 873 Class II disks in the L1641 and L1647 regions of the Orion A cloud. This sample size allows us to zoom in on variations in the median disk mass along the cloud, and to study their causes. We suggest that even in different star-forming regions, the majority of disks are formed with similar initial masses and evolve similarly if no strong external UV fields are present.

Terrestrial planets have traditionally been thought to form by collisions between protoplanets taking place mostly after the dissipation of the protoplanetary disc, on time-scales of 30-100 million years. I present here a new theoretical model where terrestrial planets grow instead by accreting small pebbles in the protoplanetary disc within 3-5 million years. I discuss how the immense pebble accretion heat leads to extensive melting of the growing planets and to the emergence of deep magma oceans. Volatiles such as water, carbon and nitrogen are accreted with the pebbles and partitioned between atmosphere, magma ocean and core. The end of the accretion phase leads to rapid crystallisation of the magma ocean and outgassing of the first planetary atmospheres. The atmospheric compositions of young planets are key to understanding the origin of life.

The peer review process is a central part of publishing in journals, but a seldom discussed aspect of our work. In this discussion, we direct a curious eye toward all parts of the process. We have invited a panel of editors to provide their perspective. We ask that you, the audience, provide the perspective of authors and referees. To do so, please fill out our survey. We will present the survey results and hope to stimulate a discussion of where we as a field need to put our attention to improve the process. The survey is available here: https://forms.office.com/r/eDYfzsJeFG

Paper: https://arxiv.org/pdf/2202.11057.pdf

FIRSTv2 (Fibered Imager foR a Single Telescope version 2) is the upgrade of a post-AO spectro-interferometer (FIRST) that enables high contrast imaging and spectroscopy at spatial scales below the diffraction limit of a single telescope. FIRST is currently installed, and routinely used, on the Subaru telescope as a module of the Subaru Extreme AO (SCExAO) platform. It achieves sensitivity and accuracy by a unique combination of sparse aperture masking, spatial filtering by single-mode fibers and cross-dispersion in the visible (600-900nm). The ongoing upgrade aims at using a photonic chip beam combiner, allowing the measurement of the complex visibility for every baseline independently. Using the integrated optics technology will increase the stability and sensitivity, and thus improve the dynamic range. Integrated optics chips working in the visible wavelength range are challenging (in terms of throughput and polarization). Several photonic chips are under characterization in our laboratory and we have installed a first prototype chip in the FIRSTv2 instrument at the Subaru Telescope. I will thus report on the on-sky results obtained with this kind of device, for the first time in the visible. This is the first step towards the full upgrade of FIRSTv2, that will ultimately provide unique capabilities to detect and characterize close companions such as exoplanets, by combining high angular resolution and spectral resolution in the visible.

The polarization model for one of the future generation telescope, the Thirty Meter Telescope (TMT) will be presented. The polarization ray tracing model gives the complete Mueller matrices of all the mirrors of the telescope. The instrumental polarization and crosstalk are found to be varying significantly with the field of view of the telescope, zenith angle, and the position of the instrument ports due to the inclined tertiary mirror of the telescope. We also propose a design to mitigate the effect of polarization arising from the Nasmyth mirror by using an inclined mirror kept orthogonal to it. The polarization aberrations arising due to the non-normal incidences and coating has been calculated to ascertain its effect on the point spread function of the telescope. The effects of the segments and coating non-uniformities have been studied. These analysis will be useful for the design of the future polarimetric instruments for TMT.

Although substantial progress has been made over the last decades on our understanding of star formation it is mostly in terms of formation of individual isolated stars. However, we know that many stars are formed in star clusters or in clustered environments. Here, the proximity of other stars and interactions between them can alter the formation of each star and thus their final properties, for example their mass. Little is known about the formation of particularly massive star clusters and their content. This is due to a combination of limited suitable targets to observe and limited sensitivity and spatial resolution of observations. As a consequence there are limited observational constraints on cluster formation models. However, in recent years suitable candidates of massive star clusters in their formation have been found. I will present our findings for several of those covering an order of magnitude in mass.

I will further discuss the end product of the star formation, the Initial Mass Function (IMF) in massive resolved star clusters. Through deep high spatial resolution imaging we have probed the low-mass content of the clusters. From this we can directly compare the derived IMF with that determined for the field and low-mass clusters. Further, through dynamic mass estimates we can determine if the clusters will remain bound or dissolve and be a component of the future field star population.

Hydrodynamical cosmological simulations are increasing their level of realism by considering more physical processes, having more resolution or larger statistics. However, one usually has to either sacrifice the statistical power of such simulations or the resolution reach within galaxies. I will introduce the NewHorizon project where a zoom-in region of ∼(16 Mpc)^3, larger than a standard zoom-in region around a single halo, embedded in a larger box is simulated at high resolution. A resolution of up to 34 pc, typical of individual zoom-in state-of-the-art resimulated halos is reached within galaxies, allowing the simulation to capture the multi-phase nature of the interstellar medium and the clumpy nature of the star formation process in galaxies. I will present and discuss several key fundamental properties of galaxies and of their black holes. Due to its exquisite spatial resolution, NewHorizon captures the inefficient process of star formation in galaxies, which evolve over time from being more turbulent, gas-rich and star-bursting at high redshift. These high redshift galaxies are also more compact, and are more elliptical, disturbed and clumpier until the level of internal gas turbulence decays enough to allow for the formation of stable rotating discs. I will show the origin and persistence of the thin and thick disc components, and explain why the settling of discs "magically" occurs at around a stellar mass of 10^10 Msun.

Paper: https://arxiv.org/abs/2202.01241

I want to introduce RECA (https://www.astroreca.org) and the many pioneer programs we are building for astronomy education in Colombia. We are a group of astronomy students and junior researchers who want to connect the new generations of students from primary school to undergraduates with global opportunities in astronomy. I would like to discuss our RECA programs and how many of you at ESO could help us grow the network with your support and advice.

A fundamental question in astrophysics is how stars get their mass. We know that low-mass stars form from the collapse of self-gravitating prestellar-cores. Since this collapse, young stellar objects (YSOs) acquire mass through the magnetospheric accretion process for up to 10Myr. According to this scenario, the material falls from the envelope through the circumstellar disk onto the central forming-star, following the magnetic field lines. Thanks to new facilities, it has been possible to observe spectroscopically the inner part of the circumstellar disks in the nerby star forming clouds. Therefore, accurate estimates of the mass accretion rate (Macc) and stellar parameters in different stages (early, i.e. ClassI, and more evolved, i.e. Classical T-Tauri stars) of the star formation process have been provided for single stars and binaries. However, if we integrate Macc provided from the observations for the estimated timescales of YSOs, we found smaller masses than we measure. This means that the majority of the mass is set during the first stage of the highly embedded protostellar phase (Class0), where planets start to form, or the accretion process proceeds in a non-steady framework. While we still know much less on accretion on Class0, the non-steady accretion is proven by the eruptive YSOs, as FUors and EXors, which experience extremely strong bursts on short and long timescales. I will review recent results about accretion, focusing on open questions on early stages, as how the forming-star mass is related to the disk and envelope mass, and the relation between models and observations.

Previous experiments have shown that in N2-dominated atmospheres lightning can lead to the formation of nitrate (NO3-) and nitrite (NO2-), which could not only have facilitated the origin of life but also sustained the earliest ecosystems. This hypothesis has been difficult to test with the available rock record because geochemical fingerprints of this fixed nitrogen source have not been developed. We present new results from spark discharge experiments in varying atmospheric compositions corresponding to different points of time in Earth’s evolution. We find substantial amounts of nitrate are produced in an N2/CO2 atmosphere. Furthermore, we investigate the effect of lightning on the isotopic composition of the resulting nitrogen oxides in solution. Our fixed nitrogen is depleted in heavy 15N in comparison to atmospheric N2, in line with rock samples older than 3.2 billion years. For the first time we can assess to what degree lightning chemistry may have influenced the origin and early evolution of life. However, the spark in our experiment is much smaller and cooler than lightning channels in Earth’s atmosphere. To extrapolate our experimental results to full-scale planetary atmospheres we complement them with a complex kinetic chemistry network which we use to simulate the atmospheric chemistry of exoplanets and Earth. We simulate the temperature decay both in a hot lightning channel and a cool spark channel, predicting the production rates of nitrogen oxides and other molecules. This allows us to extend our experiments to real lightning conditions and develop observable tracers for lightning chemistry in exoplanetary atmospheres.

The Planetary Nebula Luminosity Function (PNLF) that goes back to the empirical discovery of an invariant bright cut-off, regardless of Hubble type and metallicity of the host galaxy, has been used since 1989 as a distance indicator for galaxies with a distance of up to ~20 Mpc. Based on narrow-band filter photometry in [OIII] 5007, mainly using 4m class telescopes, this distance range has been explored to saturation. We have found, using MUSE datacubes from the ESO Archive, that a new differential filter technique (DELF) is capable of providing [OIII] photometry with unprecedented sensitivity and accuracy, thus expanding the reach of PNLF distances out to > 30 Mpc, with a distance modulus accuracy of 0.04 mag. I will review recent MUSE PNLF work of several groups, present the benefits of the DELF approach, and explain the potential to measure Ho with this new, independent technique.

Vertical shear instability (VSI) is a robust and potentially important phenomenon in irradiated protoplanetary disks (PPDs), yet the mechanism by which it saturates remains poorly understood. Global simulations suggest that the non-linear evolution of the VSI is dominated by radially propagating inertial wavetrains (called ‘body modes’), but these are known to be susceptible to a parametric instability. In this talk, I will present our recent results on the saturation of VSI via this parametric instability. An analytic theory of the instability in a simple idealised model was introduced and numerical simulations with the SNOOPY code were conducted to consolidate the theory. Once the parametric instability prevails, the VSI is likely far more disordered and incoherent than current global simulations suggest.

The results of LIGO and Virgo open a new landscape for the study of binary black holes: we now know of nearly one hundred candidate systems. Because of the new data, theoretical and numerical models of binary black hole formation face a serious challenge: several LIGO-Virgo black holes have mass in the upper mass gap (~60-120 Msun) predicted by pair-instability theory, others partially overlap with the lower mass gap (~2-5 Msun). On the one hand, population models of massive binary stars predict black hole masses in the range ~ 3 - 50 Msun, with nearly aligned spins, but are affected by large uncertainties. On the other hand, dynamics of dense stellar clusters can trigger the formation of binary black holes with largely misaligned spins, and even fill the pair instability mass gap. In this talk, I will present new theoretical models of the formation of massive (>60 Msun) black holes via multiple stellar collisions and hierarchical mergers of low-mass black holes in dense star clusters. Furthermore, the redshift evolution of binary black holes is one of the key features to understand their formation, in preparation for next-generation gravitational-wave detectors.

Paper: https://arxiv.org/pdf/2202.09285.pdf

Understanding the physical processes responsible for ceasing star formation in galaxies is one of the most important unresolved questions in the field of galaxy evolution. Over the past two decades multiple mechanisms were suggested as potential drivers of the transition between the star-forming and quiescent galaxy categories, referred to as galaxy ‘quenching’. In this talk I will present the results of our recent study, in which we combine machine learning with partial correlation analysis to determine which among the three potential quenching mechanisms: supernova feedback, halo shock heating or AGN feedback are most likely responsible for bringing star formation to a halt in massive, central galaxies. To this end we bridge the gap between theory and observation by extracting theoretical predictions from three state-of-the-art cosmological simulations – EAGLE, Illustris and IllustrisTNG and comparing them with the Sloan Digital Sky Survey (SDSS) observations. We find that the supermassive black hole mass (MBH) is the most powerful parameter in determining whether a galaxy is star-forming or quenched across all datasets. Remarkably, this result is true for all different implementations of AGN feedback in the simulations and is met overwhelmingly well in the SDSS, where we infer MBH from a variety of calibrations for ~230 000 local galaxies. In my brief talk I will share our results together with our methodology to make a convincing case for star formation being quenched by AGN in massive, central galaxies. If you would like to learn more about this study, you can now read it on arXiv/MNRAS at the following link: https://arxiv.org/abs/2112.07672

Compact star formation appears to be generally common in dusty star-forming galaxies. However, it remains to be understood how systematic compactness is and its role in the framework set by the scaling relations in galaxy evolution. GOODS-ALMA is a 1.1mm galaxy survey over a continuous area of 72 arcmin2 at a homogeneous sensitivity with two array configurations aimed at understanding these questions. In this new version 2.0 we present a new low-resolution dataset and its combination with the previous high-resolution dataset. The latest results reveal that dust continuum emission at 1.1mm prevails, and sizes as extended as typical star-forming stellar disks are rare. A population of galaxies with modest star formation rates, but which exhibit extremely compact star formation with starburst-like depletion timescales unveils. Compact star formation appears as a physical driver of depletion timescales, gas fractions, and dust temperatures. The new findings suggest that the star formation rate is sustained in very massive SFGs, even when their gas fractions are low and they are presumably on the way to quiescence. Gas and star formation compression seems to be a mechanism that allows to hold their star formation rate.

The cold dark matter picture predicts an abundance of substructure within the Galactic halo. However, most substructures host no stars and can only be detected indirectly. Stellar streams present a promising probe of this dark substructure. These streams arise from tidally stripped star clusters or dwarf galaxies, and their low dynamical temperature and negligible self-gravity give them a sharp memory of past gravitational perturbations. Due to this feature, perturbed stellar streams have been the subject of substantial study. I will review these studies, which are largely numerical, before showing that in the diffusion regime -- where a stream is subjected to many substructure encounters -- perturbations to the stream can be understood on a fully analytic level. This analytic description cleanly connects the response of a stellar stream to the statistics of the perturbing environment, which may include both dark and luminous substructure.

The observational study of the interplay between galaxy angular momentum and structure in the cosmic web is challenging due to the weakness of the signal. We study the alignments of galaxy spin axes with respect to cosmic web filaments as a function of different properties for galaxies and for their bulge and disk components. We exploit the SAMI Galaxy Survey to identify 3D spin axes from spatially-resolved kinematics and to decompose galaxies into their kinematic bulge and disk components. We use the GAMA spectroscopic survey to reconstruct the surrounding cosmic filaments. We find a strong correlation between the galaxy spin-filament alignment and the mass of the bulge: galaxies with lower bulge masses tend to have their spins parallel to the closest filament, while high-bulge mass galaxies show a perpendicular orientation. This observed link between the flip in the spin-filament alignment and the growth of the bulge can be explained by mergers. Bulges tend tohave perpendicular alignments, indicating mergers as their main formation channel; in contrast, pseudo-bulges tend to have a parallel alignment, consistent with secular accretion. Disks show different alignments according to their kinematic features and bulge mass, suggesting varying formation pathways. We conclude that bulge mass is the primary parameter tracing the processes that cause the galaxy spin-filament alignment to flip from parallel to perpendicular.

In Astronomy, interferometry is an observational technique that delivers us the major resolution possible to study physical processes at the smallest spatial scales that we can probe with our instruments. It is used extensively at radio wavelengths and, since more than a decade, it has been converted into an important technique for infrared Astronomy. Nowadays, the new generation of Very Large Telescope Interferomery instruments have allowed us to recover infrared milliarcsecond-resolution images with good quality to perform detailed scientific analysis from them. As part of the Guaranteed Time Observation’s program of GRAVITY, we have used image reconstruction to analyze several Young Stellar Objects with the aim of depicting their complex morphologies. In this talk, I will give a quick overview of the imaging techniques used in infrared interferometry and, I will highlight their usability with on-sky Hergibg YSO observations taken with GRAVITY at the VLTI.

Supernovae ultimately deposit ~10% of their total energy in a population of relativistic cosmic rays that subsequently interact with the interstellar medium (ISM) via magnetic forces. Because these particles lose energy to radiation only slowly compared to the ~90% of the supernova energy that is deposited in the ISM as heat, they are a potentially important feedback mechanism in galaxies despite their comparatively small energy budget. Their effectiveness, however, depends crucially on the poorly-understood plasma processes that couple them to the bulk, neutral ISM. In this talk I introduce a new, physically-motivated model for the coupling between cosmic rays and the neutral, star-forming ISM, and show that it successfully predicts the gamma-ray spectra of resolved nearby galaxies, the galactic IR-gamma correlation, and the cosmological gamma-ray background. I conclude by exploring the implications of
this model for the importance of cosmic ray feedback, demonstrating that this mechanism is likely unimportant for rapidly star-forming galaxies either today or in the early universe, but may be critical for local dwarfs and quiescent spirals.

Paper: https://arxiv.org/pdf/2202.05301.pdf

The idea of turning data into sound is not new; however, over the last decade there has been a dramatic increase in the number of projects using sound for astronomy research, communication and education. I will present a brief overview of the 98 such projects we identified (as of December 2021) that form the basis of our recently submitted review article. Through some examples, I will discuss the large potential benefits of using sound to both enhance scientific discovery and to make astronomy more accessible and engaging for a wide variety of audiences. On the flip-side, I will present some of the challenges and limitations that have limited the progress in using sound within the mainstream astronomy research and communication communities. At the present time North America and Australia are leading the way in resolving these issues and are embracing these new sound-based approaches. Therefore, during this session I welcome a discussion on how ESO and the European astronomy community might make more progress in this arena and take the lead in unleashing the huge potential of sonification and sound design.

The extended, fragile, collisional atomic hydrogen (HI) gas discs in galaxies are excellent diagnostic tracers of gravitational and hydrodynamic processes in the cosmic environment they are residing in and also reservoirs for star formation. Within a galaxy cluster, both gravitational perturbations (tidal interactions, harassment, etc.) and hydrodynamic processes (thermal evaporation, ram pressure stripping (RPS), etc.) are at play. However, it is not clear yet which of these processes dominate the transformation of galaxies from star forming and gas rich, to quiescent and gas poor. I am investigating the influences of the global and local cosmic environment on the evolution of galaxies, both from the HI morphologies of galaxies in different locations of cluster substructures and the multi-wavelength case studies of the striking galaxies. From the new MeerKAT telescope observations of A2626 volume, I am studying the spatially resolved morphologies of the 219 HI detected galaxies, covering a range of cosmic environments. By identifying the cluster substructures and characterising their environments, I investigate the relative importance and effects of the various physical mechanisms that are responsible for reshaping galaxies. In addition, I am also studying the detailed cases of HI gas stripping in the “jellyfish galaxies”, the extreme examples of RPS with in-situ star formation in the tails. I have analysed the multi-phase (neutral, molecular, ionised gas) ISM of jellyfish galaxies JW100 and JO204 from multi-wavelength MeerKAT or JVLA, MUSE and ALMA observations. I will talk about how HI observations contribute to understanding the multiphase gas stripping in these jellyfish galaxies.

The first epoch of galaxy formation is governed by the infall of neutral, pristine gas. These neutral atomic hydrogen (HI) gas reservoirs will subsequently cool and condense into molecular clouds and initiate star-formation. The HI gas content is therefore a key ingredient in the overall process of galaxy evolution. In the local Universe the hyperfine HI 21-cm transition has been used as the main tracer of this neutral atomic gas, but due to the weakness of the line this approach is only feasible at moderate lookback distances for individual galaxies, even with next generation radio observatories. In this talk I will present a new approach to infer the HI gas mass of high-redshift galaxies, based on an empirical measurement of the [CII]-to-HI conversion factor using gamma-ray bursts. These bright cosmic beacons are used to illuminate the column density ratio of HI and [CII], which provides a scaling between the HI mass and [CII] luminosity per unit column in the line of sight.

I will demonstrate how this conversion factor can be applied to recent galaxy samples surveying [CII] out to the edge of the epoch of reionization, at z~6. The HI gas mass is found to exceed the stellar mass at redshifts greater than z~1, and to increase as a function of redshift. Similarly, the fraction of HI to the total baryonic mass of these galaxies is observed to increases from around 25% at z=0 to about 60% at z~6. Further, I will show how the association of [CII] with HI also naturally explains the observed, more extended [CII] emission maps of high-redshift galaxies. I will also demonstrate how this technique makes it possible to infer the cosmic HI gas mass density in galaxies from z~6 to the present, based on estimates of the [CII] luminosity density. These results show the baryonic matter of star-forming galaxies in the early Universe is dominated by neutral atomic gas, a vital component to take into account when determining the gas available to initiate and maintain star formation.

Self-gravity is an essential ingredient to determine the dynamics of young protoplanetary discs, since their mass can be a considerable fraction of the stellar one, and the system may develop gravitational instability (GI). The characteristic signature of GI is the presence of a spiral perturbation, that deeply influences disc evolution, since it efficiently redistributes angular momentum among the system. Recent observations are showing that planet formation is already underway in young systems, so assessing the role of GI is crucial to fully understand this process.

In this talk I am going to present both kinematical signatures and dynamical effects of gravitationally instability. As for the kinematics, the spiral perturbation strongly perturbs the velocity field, leaving clear kinematic features in molecular line emission. These imprints, dubbed as “GI wiggles”, can give us insight about the thermodynamics of the system, allowing us to estimate its cooling time. As for the dynamics, I am interested in the role of dust in GI. Gas spiral arms are minima of gravitational potential, and maxima of the pressure: for this reason, solid particles tend to concentrate inside them. In addition, dust conditions in spiral arms are unstable, and it is likely that it collapses in gravitationally bounded fragments. Through analytical arguments and numerical simulations, we want to deeply study dust properties in gravitationally unstable discs, and understand whether planets can formed in these environments.

The eROSITA Final Equatorial-Depth Survey (eFEDS) is a 140 square degree area observed during the performance verification phase of eROSITA. It was observed at a similar depth to the expected exposure in the final all-sky survey in equatorial regions. In this area, we detect 542 clusters. We have studied the morphological properties of the eFEDS clusters by modelling how these properties depend on redshift and luminosity. Using a novel technique, we combine 12 morphology estimators in a single measurement that indicate the relaxation state of the detected clusters. We further investigate the underlying cluster populations (with relaxed and unrelaxed morphology) in the eFEDS cluster sample and find that a simple unimodal distribution is always preferred in this sample. Finally, we investigate the redshift evolution of the relaxed cluster fraction and find no evidence for significant redshift evolution. I will present the methods and results of this work, which you can find at arXiv:2106.15086.

Massive stars play important roles in many astrophysical systems by providing the radiative and mechanical energy output. They can also produce black holes and neutron stars when they explode. However, the traditional 1D stellar evolution models provide very uncertain predictions for the structure and evolution of massive stars because radiation acceleration around the envelopes of massive stars at the iron opacity regions can be much larger than the gravitational acceleration. I will show how we can understand convection in massive star envelopes and observational properties of massive stars in different locations of the HR diagram based on a series of first principle global 3D radiation hydrodynamic simulations. These simulations can be used to understand the physical origin of super-Eddington outflows from massive stars and the outburst behavior of luminous blue variables. I will demonstrate these simulations can directly produce the low frequency variabilities of many O stars as observed by TESS recently. I will also show simulations of Red Supergiants, which are used to predict observational properties of supernova shock breakouts. Finally, I will illustrate how these simulation results can be used to improve the traditional 1D stellar evolution calculations, which can provide much more reliable models of massive stars.

Paper: https://arxiv.org/pdf/2112.09160.pdf

Over the last few periods, VLTI operations have adapted better to science cases requiring imaging or monitoring of variable targets, and the European network of expertise centers offers help with proposal preparation and even full data reduction and calibration.  The astrometric mode of GRAVITY and mid-infrared imaging with MATISSE have attracted more astronomers who recognize the unique capabilities these instruments have for their science projects. However, preparing a proposal including the description of astrophysical constraints to be delivered by the interferometric observations is challenging for newcomers, and I my presentation I will highlight the use of interferometry for some of these science cases.

High-redshift quasars can shed light on the co-evolution of central supermassive black holes and their host galaxies in the very early universe. Observational constraints on radio jet and interstellar medium feedback processes are still very limited at redshifts z>2. We investigate the radio-loud quasar P352-15 near the end of Reionization at redshift z~6. This quasar is the most powerful radio emitter with direct evidence of a kpc-scale radio jet (~1.6 kpc) at these high redshifts. I will present the results on the spectral energy distribution of this quasar at millimeter (far-infrared in the rest-frame) and radio observations. The millimeter continuum emission for radio-quiet quasars at these redshifts has usually been interpreted as cold dust and is modeled as a modified black body. However, the analysis on this radio-loud quasar shows that it is not possible to model the millimeter measurements as cold dust alone. I will present evidence of the strong radio synchrotron emission in this source affecting the dust-dominated continuum emission in the millimeter, and implying a break in the synchrotron spectrum. I will further portray the big picture in a dedicated study for the first time on measuring different jet lifetimes based on rest-UV/Optical and radio observations of this quasar. Thus, constraining the black hole - host galaxy formation and jet ejection mechanisms of a quasar in the first Gyr of the universe.

The usual choice of adopting simple power-law scaling relations to link the total mass of members with their luminosity is one of the possible inherent systematics within strong lensing (SL) models of galaxy clusters, and therefore on the derived cluster masses.

I will present how we use the Fundamental Plane (FP) relation to obtain more accurate and complex relations between the observables describing cluster members, and to completely fix their mass from their observed magnitudes and effective radii. Using new information on their structural parameters (from HST imaging) and kinematics (from MUSE data), we build the FP for the early-type galaxies of the cluster Abell S1063. We take advantage of the calibrated FP to develop an improved SL model of the total mass of the cluster core.

The new method allows for a reduction of the uncertainty on the value of the core radius of the main DM halo. We also find a different relation between the mass and the velocity dispersion of members, which shows a significant scatter. Thanks to a new estimate of the stellar mass of cluster members from HST data, we measure the two-dimensional, cumulative mass profiles out to a radius of 350 kpc, for all baryonic and dark matter components of the cluster. Finally, I will present a comparison between the physical properties of sub-halo in our model and those predicted by high-resolution hydrodynamical simulations. We find good agreement in terms of stellar mass fraction, and some discrepancies in terms of sub-halo compactness.

Dust is one of the most important components of the ISM in galaxies. It is a key element in determining the physics and chemistry of the ISM, has crucial roles in the star formation process, and shapes the UV-to-IR SED of galaxies across cosmic time. At Cosmic Noon, z~1-3, most of the energy of galaxies with masses >1e9 Msun is radiated at dust-reprocessed IR wavelengths, yet our understanding of the properties of dust in typical galaxies at these redshifts is far from complete. In this talk, I will show the results of our deep targeted ALMA band-6 continuum survey of ~30 galaxies at z=2.1-2.5, tracing the Rayleigh-Jeans tail of the dust emission. We have robust gas metallicity and SFR estimates for the sample from a suit of optical emission lines, including Hb, [OIII]5008, Ha, and [NII]6585, from the MOSFIRE spectrometer on Keck (the MOSDEF survey). Combining the ALMA continuum observations and Keck spectra with the Spitzer 24um and Herschel 100, 160, and 250um photometry, we study, for the first time, the evolution of the IR SED and dust masses with metallicity at z~2, and compare them with those at z~0. Our data indicates an evolution in the shape of the IR SED with metallicity at z~2, as well as an order of magnitude evolution in dust masses at a given metallicity from z~0 to 2.

I will conclude the talk with a JWST/MIRI prospect. As part of the JWST MIRI HUDF Survey (US MIRI GTO program), we plan to observe the mid-IR dust emission of z~1-3 galaxies in all 8 bands of MIRI from 5 to 28um, providing a very low resolution (R~5) mid-IR spectra. These rich observations will provide constraints to better characterize the IR SED of Cosmic Noon galaxies -- in particular, the relative contribution of hot dust continuum emission and aromatic bands in the mid-IR spectra -- for the first time down to the LIRG regime and below at z>1.

These are incredibly exciting times for extra-galactic astrophysics; above all for studies of galaxy formation and growth of structure. New observatories and advanced simulations are revolutionising our understanding of the cycling of matter into, through, and out of galaxies. In this talk I will provide an overview of the normal matter in collapsed structures, their chemical make-up and dust content. I will present fresh clues of the cosmic evolution of cold gas; revisit the 20-year old "missing metals problem" and introduce new calculations of the dust content of the Universe up to early times. Together, these results provide an increasingly accurate description of the baryon cycle which plays many crucial roles in transforming the bare pristine Universe left after the Big Bang into the rich and diverse Universe in which we live today.

Paper: https://arxiv.org/pdf/2112.04538.pdf

For its Cycle 8, ALMA implemented two major changes in the proposal selection procedure. Dual-anonymous review in which the identity of the proposers was not revealed to the reviewers was introduced, and at the same time distributed peer review was adopted to award the majority of the observing time. Nearly 1500 proposals were assessed using this method, making it the largest implementation of distributed peer review in astronomy to date. In this Informal Discussion, we will give an overview of the ALMA proposal selection process, discuss some effects seen in e.g. the change of the amount of time requested per proposal, describe how the distributed peer review works in practice and highlight some interesting trends, correlations, and feedback from PIs.

To form giant planets during protoplanetary disk lifetime, small micron sized particles must grow rapidly to larger grains. A full understanding of that process requires a detailed characterization of the radial and vertical structure of the gas-rich disks associated with young pre-main sequence stars. Multi-wavelengths observations of protoplanetary disks, for example in the millimeter and near-infrared, allow to probe two widely separated grain sizes that are differently affected by evolutionary mechanisms such as radial drift and vertical settling. In this talk, I will present constraints on both mechanisms using multi wavelengths observations, with a longer focus on disks seen edge-on. Highly inclined disks are of particular interest because they provide a unique point of view to unambiguously disentangle their vertical and radial dimensions. The modeling of multi-wavelength observations of such disks allows to identify high density regions, favorable for grain growth and planet formation, and to study the efficiency of planet formation in protoplanetary disks.

I will present the first results on galaxy clusters from the eROSITA early observations and multiwavelength follow-up, with an emphasis on eFEDS, a 140 deg2 proof-of-concept mini-survey conducted during the PV phase. We detected 542 candidate clusters as extended sources in the eFEDS survey, and studied their X-ray properties with eROSITA data. I will overview the eFEDS galaxy cluster catalog, and highlight the scientific results we obtained on the eFEDS clusters. I will also briefly introduce our most recent progress on galaxy clusters in the eROSITA All-Sky Survey.

If Earth lost its magnetic field, would its ability to support life be diminished? If Mars had retained a strong magnetic field, would it be habitable today? For decades it was assumed that the answers to these two questions were “yes”. In recent years, however, the canonical assumption that planetary magnetic fields improve planetary habitability has been called into question. This presentation will review the perceived connections between magnetic fields and surface and atmospheric habitability of planets and discuss several approaches to resolving this important question: (1) intercomparison of observations of Venus, Earth, and Mars, (2) analysis of observations from unmagnetized and magnetized regions of Mars, and (3) development of large computer simulations for the interaction of a star with a planet’s atmosphere and magnetic field. In the end, all approaches are likely to be necessary. We will discuss an ongoing team science effort named MACH that draws on expertise from the heliophysics, planetary, and exoplanetary communities.

paper: https://arxiv.org/abs/2112.02111

https://www.google.com/url?q=https://arxiv.org/abs/2112.02111&sa=D&source=calendar&usd=2&usg=AOvVaw30M9klv33m9o0PQ65bUcWd

Dwarf galaxies, such as those orbiting the Milky Way, are believed to be excellent testbeds in which to study dark matter. Their internal kinematics indicate that these are amongst the most dark matter-dominated objects in the Universe. Their relative proximity allows the collection of high-quality spectroscopic, photometric and proper motion data. These data contain crucial information on the inner structure of halos, which sets an important constraint on the particle physics properties of dark matter. However, high-resolution N-body hydrodynamics simulations suggest that the dark matter distribution in dwarf galaxies is also sensitive to the physics of galaxy formation, the details of which are not fully understood. In this talk, I will review the current status of dark matter studies in Galactic dwarf galaxies and the challenges we face in both observations and simulations.

In Astronomy, interferometry is an observational technique that delivers us the major resolution possible to study physical processes at the smallest spatial scales that we can probe with our instruments. It is used extensively at radio wavelengths and, since more than a decade, it has been converted into an important technique for infrared Astronomy. However, in the infrared interferometry is restricted to the use of arrays with only a few telescopes. Meanwhile interferometric imaging is the most intuitive way to understand the data, recovering images from sparse arrays is an “ill-posed” problem, with less data (equations) than pixels (unknowns) to recover. In this talk, we will present the basic concepts for image infrared image reconstruction. In particular, we will present some examples of imaging cases observed with the near-infrared instrument GRAVITY at the Very Large Telescope Interferometer. Finally, we will describe the areas of opportunity to improve interferometric imaging.

The galaxy luminosity function (GLF) is a basic descriptor of the galaxy population and its evolution though the history of the Universe. I will present a new experimental design using clustering-based redshift inference to measure the evolving galaxy luminosity function. The idea is to exploit the fact that galaxies are not uniformly distributed through space; instead are strongly clustered and it is therefore possible to infer the statistical distribution of  distances.
 
We derive the GLF using data from the Galaxy And Mass Assembly (GAMA) survey and the Kilo-Degree Survey (KiDS) to the limits of the GAMA-KiDS photometric catalogue: m_r ~ 23; more than a decade in luminosity beyond the limits of the GAMA spectroscopic redshift sample.
 
We find that the GLF has a relatively constant power-law slope α ≈ −1.2 for M_r < −13, and then appears to steepen sharply. This upturn appears to be where Globular Clusters (GCs) take over to dominate the source counts as a function of luminosity. Thus we have mapped the GLF across the full range of the z~0 field galaxy population from the most luminous galaxies down to the GC scale.

During merging, the tidal forces of a giant galaxy can strip away the contents of a smaller one leaving behind the nuclear star cluster to orbit in the halo of the giant galaxy as a stripped galaxy nuclei. These stripped nuclei hide among the most luminous globular clusters (GCs) in the halo of galaxies and can be challenging to distinguish. The collection of massive GCs and stripped galaxy nuclei are often called ultra-compact dwarf galaxies (UCDs). An exciting confirmation of this theory is the detection of overmassive black holes in the centers of some UCDs, which also lead to elevated dynamical mass-to-light ratios compared with regular massive GCs.

Here I present new high-resolution spectroscopic observations of 321 luminous GC idates in Centaurus A. Centaurus A is the closest giant elliptical and may have undergone a significant merger event, thus providing a unique comparison framework for substructures with the Local Group, such as stripped galaxy nuclei. This work represents the most complete catalog of dynamical mass measurements of luminous GCs in Centaurus A. Our results show a bi-modality in the dynamical mass-to-light ratio distribution, with a population of "normal" GCs and a second population with elevated mass-to-light ratios. This bi modal distribution deviates significantly from the GC distribution in the Local Group. I will also show that massive central black holes of 10% of the luminous GC virial mass can explain the observed elevated mass-to-light ratios, suggesting that some of these luminous GCs in Centaurus A are stripped galaxy nuclei.

The relative impact of different quenching mechanisms in galaxies at different cosmic epochs is still unknown. In particular, the relation between these processes and morphological transformation remains with understanding gaps. In this work we study the relation of star formation variations in the past 300 Myrs in galaxies with different morphologies. For a sample with ~14,200 spirals and ~2,500 ellipticals, our main findings are: elliptical galaxies in the green valley have shorter quenching timescales, in accordance with the major merger scenario; massive asymmetric spirals are the main galaxies bursting in the green valley, following the scenario where minor mergers can trigger star formation and disturb their morphology. Lastly, we present a broader scenario for galaxy evolution in the colour-magnitude diagram following our recent findings.

The meeting will be 2G and everyone is welcome.

The International Staff Association exists to defend the interests and rights of its members, and those members are you! Come along to hear how the ISC aims to fulfil the aims of the association and for a chance to meet some of the current committee representatives. We welcome your questions and look forward to an open discussion about how the ISA can help you.

Paper: https://arxiv.org/abs/2111.07573

The successful Kepler and TESS missions have discovered thousands of exoplanets and let the community focus on the characterisation of these bodies. One area of research utilises ultra-high-precision photometric and spectroscopic follow-up observations in order to accurately constrain the bulk densities of terrestrial exoplanets. Combining these observables with Bayesian internal structure modelling that uses geological equations of state, we can start to learn about the compositions of planets around main-sequence stars for the first time. Importantly, by studying multi-planet systems we can conduct comparative planetology that can reveal important aspects that challenge our knowledge of planet formation and evolution via the contrastment of the observational and modelling results of a planet against its neighbours.

In this talk, I will present observational studies characterising multi-planet systems initially discovered with TESS and followed-up with the CHEOPS satellite and ground-based instruments, such as ESPRESSO. Additionally, I will discuss our Bayesian internal structure and atmospheric escape modelling, and present the results of utilising such models on several key, multi-planet systems observed with CHEOPS that are expected to become cornerstones of exoplanet characterisation due to the questions they raise about planet formation, the system multiplicity, or the amenability to atmospheric observations. Important knowledge about these systems was uncovered via a combination of precise observations using a new generation of instruments and cutting-edge planetary internal structure modelling. Therefore, utilising these resources we are at the beginning of a new era in characterising terrestrial bodies outside of our Solar System that will be strengthened with JWST.

According to the core accretion theory, rocky planets form by growing the initial micron-sized dust in protoplanetary discs up to the size of a planet. When the grains reach the size of 1 cm, however, the growth process faces a critical stage: the interaction with the disc gaseous component causes the cm-sized grains to drift rapidly towards the central star, becoming unavailable to form planets. Streaming instability (SI) is often invoked as a potential solution, as it promotes rapid dust overdensity formation. In my study, I simulated the action of SI through 2D local simulations, and computed the mm emission of resulting dusty clumps. Although the small size of the resulting dust clumps makes them inaccessible by direct observations (and thus we cannot directly compare the computed emission to the data), it is possible to define observable quantities, from which we can infer the presence of such substructures. By focusing on two observables – the optically thick fraction ff (in ALMA band 6) and the spectral index alpha (in bands 3-7) – I compared the distribution of simulations in the ff-alpha plane before/after the action of streaming instability to recent multiwavelength data in the Lupus star forming region, finding that the action of SI drives the simulations towards the area of the plane occupied by the data. This study therefore suggests that clump formation via SI is consistent with recent observations, confirming that it can be considered a good idate to solve the radial drift barrier to planetesimal formation.

The Hubble Space Telescope archives can hide many unexpected treasures, such as trails of asteroids, showing a characteristic curvature due to the parallax induced by the orbital motion of the spacecraft during the exposures. I present recent results from the www.asteroidhunter.org project, exploring the ESA Hubble Space Telescope archives with citizen science and deep learning for serendipitously observed asteroids and artificial satellites in orbits higher than Hubble's. We find 1700 asteroid trails in the past twenty years of Hubble observations, most of them being faint and yet to be identified. Additionally, we measure, for the first time, the fraction of Hubble images impacted by artificial satellites for different instruments, filters, and as a function of time, showing that satellites can impact not only observations from the ground but also those from low-Earth orbit. Finally, I will argue that a combination of citizen science and artificial intelligence methods is an efficient way of exploring increasingly large datasets by taking full advantage of the intuition of the human brain and the processing power of machine learning, thus enhancing the scientific exploitation of data archives.

ALMA has changed our understanding of star and planet formation through sensitive and high-resolution observations that unveiled new aspects of the dust and gas distribution around protostars, their kinematics and chemical evolution. In this talk, I will present an overview of the Barnard 59 core, the only site actively forming stars in the otherwise quiescent and magnetized Pipe molecular cloud. ALMA observations revealed dust and molecular gas accretion streamers nurturing young stellar objects in Barnard 59. While some of these streamers are seen in connection with a growing binary system (the "cosmic pretzel" [BHB2007] 11), others were observed infalling into a protoplanetary disk, showing that accretion is continuing for times longer than previously thought, affecting the dynamics and possibly the chemistry of the future planetary system. At larger scales, the core itself is nurtured by a filament that is disrupting the cloud magnetic field, as also observed recently in other star-forming regions. I will also briefly discuss the self-similar aspect of accretion from cloud to disk scales the Pipe nebula.

Black holes are ubiquitous throughout the universe, being born at the earliest times, lurking at the centres of galaxies, roaming undetected through local space, and at the heart of the most extreme astrophysical transients: GRBs, TDEs and gravitational wave bursts. It is the interaction between two coupled phenomena in the direct environment of the black hole, accretion and outflow, which largely determine how we observe these bizarre objects. Relativistic outflows or jets are usually detected via the synchrotron signature associated with relativistic electrons, and the radio band is the best place to see this signature. In this talk I will highlight new advances in the understanding of jets, their power and their propagation through the ambient medium. This will be discussed in the context of jets from stellar mass black holes in binary systems, but has a broader context applicable to all black holes. In particular I will focus on what three years of observations with MeerKAT, as part of the ThunderKAT project, have revealed to us about the large-scale propagation and deceleration of powerful jets from the very moment of launch to their terminal deceleration in the interstellar medium approximately one year later.

Understanding the lives and interior structures of stellar objects is a fundamental objective of astrophysics. Research in this domain often relies on the visualization of astrophysical data, for instance the results of theoretical simulations. However, the diagrams commonly employed to this effect are usually static, complex, and can sometimes be non-intuitive or even counter-intuitive to newcomers in the field.

In this informal talk I will introduce the python package TULIPS, which enables interactive visualization of stellar models computed with the MESA code. The audience will have the opportunity to try out TULIPS themselves through a hands-on interactive tutorial that makes use of jupyter notebooks. I will discuss applications of TULIPS for research, higher education, and outreach.

To try out TULIPS, please make sure to download the following:

• TULIPS: easiest through `pip install astro-tulips`, more information at https://astro-tulips.readthedocs.io/
• An example stellar model: the file single_11Msun.tar.gz at https://zenodo.org/record/5032250
• jupyter needs to be installed (for example through the Anaconda python distribution: https://www.anaconda.com/products/individual)

The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova (SN) and dictate the appearance of the resulting explosion. Particularly important in how stars appear in the run-up to core-collapse, and in how the explosion will appear, is the amount of mass lost through stellar winds in the RSG phase that immediately precedes SN. Specifically, there have been many recent claims in the literature that stars with masses >17Msun must experience an extended period of enhanced mass-loss before SN in which the envelope is entirely lost. To study how mass‐loss rates change with evolution, we focus on measuring the mass‐loss rates of RSGs in a sample of clusters in the local Universe. The results indicate that there is little justification for substantially increasing the mass loss rates during the RSG phase. In fact, I have shown that for the more massive RSG the mass-loss rates used in evolutionary simulations must be *decreased* by up to a factor of 20. Implementing this new mass-loss rate equation into stellar models shows stars < 30Msun cannot have their envelopes stripped through quiescent winds prior to core-collapse. I will also discuss the potential for extreme mass-loss rate phases that have been proposed to take place over a short amount of time, but with the potential to peel away many Solar masses of material. Ultimately, I will discuss prospects for the single star evolutionary pathway for the formation of Type Ibc SNe.

For decades, astronomers have been investigating the connection between supermassive black holes (SMBH) and their host galaxies.

I will talk about my work based on the largest-yet sample of galaxies with dynamically measured central SMBH masses, which adds another step to this study. We measured the host galaxy properties using state-of-the-art two-dimensional isophotal modeling and the multi-component photometric decomposition, incorporating the kinematic evidence for the presence of stellar disks. These decompositions allowed us to accurately estimate the galactic spheroid properties and reliably identify the galaxy morphologies. We investigated the BH mass scaling relations for various sub-morphological classes of galaxies, i.e., galaxies with and without a disk, early-type versus late-type galaxies, barred versus non-barred galaxies, and Sersic (gas-abundant accretion/wet merger) versus core-Sersic (depleted-core, dry merger) galaxies.

Consequently, we have discovered significantly modified correlations of BH mass with galaxy properties, e.g., the spheroid stellar mass, total galaxy stellar mass, central stellar velocity dispersion, bulge central light concentration, bulge size, and the bulge projected and internal stellar. The final scaling relations are dependent on galaxy morphology, fundamentally linked with galaxy formation and evolutionary paths. These relations provide consistent predictions for the very recent directly measured BHs. The morphological dependence of BH scaling relations poses ramifications for the virial factor and offers tests for simulations and theories for BH-galaxy co-evolution. These relations provide an easier way to estimate BH merger time scales, morphology-aware BH mass function, and improved characteristic strain model for the ground- and space-based detection of long-wavelength gravitational waves generated by merging SMBHs.

The majority of AGN growth is likely to be in heavily obscured phases, but how do these appear? Are they transient phases that are quickly lost, or can we see stable states of complete obscuration? Using the massive dataset of SDSS/BOSS optical spectroscopy along with the all-sky WISE IR survey, I selected quasar-bright galaxies, with AGN-like mid-IR colours, but lacking major optical signatures (principally [O III] emission). These are AGN that may represent an interesting and understudied phase in the obscured growth of AGN. In this talk I will explain the motivation and methodology of this search, and present some details of the Optically Quiescent Quasar population.

Planet formation is a natural consequence of the star formation process, and there is an incredible variety of planetary systems, which are significantly different from the Solar System. Recent ALMA observations have revealed chemistry in planet-forming regions, protoplanetary disks. Various complex organic molecules are found in the disk forming regions, and their abundances vary significantly among objects. This indicates that the Solar System may not have been common in terms of its initial chemistry, which invokes the discussion on the rarity of our existence. To tackle this question, multi-faceted approaches are required. I will introduce such efforts in Japan along with recent observational/experimental studies.

Paper: https://arxiv.org/pdf/2110.09684.pdf

Streaks in astronomical images can either be an undesired obstacle for the analysis or the target of some observations. An example of the former are satellite tails in deep sky images, an example of the latter are near solar system objects. It is crucial to find them automatically in large surveys in both cases. We present a novel streak pattern representation called steerable representation, allowing noticeably faster processing time at a higher memory cost. Steerable representation compresses a template into a vector of size k, where k is negligible wrt the size of the represented template. Such representation allows to (1) compute an arbitrarily oriented streak response in O(k), (2) compute an arbitrarily oriented streak response for a set of k lengths in amortized O(1). Moreover, the steerable representation allows computing additional (steerable) features together with streak (ridge) responses (such as ridge-ends, rotation-invariant upper-bounds, edges, and ridge derivations by angle). Results show that we can compute response approximately 30 folds faster than without steerable representation, with a detection quality comparable to the state-of-the-art approach.

Cold gas is the fuel for star formation and mapping the evolution of the cosmic molecular gas content is therefore key to our understanding of the build-up of galaxies over cosmic time. The advent of large millimeter interferometers now makes it possible to map the cold gas content of the universe in unprecedented detail. In this talk, I will present the latest results from the ALMA Spectroscopic Survey of the Hubble Ultra Deep Field (ASPECS), an ALMA large program that performed the largest three dimensional spectral-scan survey for cold gas and dust through cosmic time. I will discuss the resulting physical properties and conditions inside the cold interstellar medium of star-forming galaxies at cosmic noon, and the implications of ASPECS for the cosmic molecular gas density and the baryon cycle. I will close by discussing key steps we are working on to further refine our knowledge of cold gas in distant galaxies.

ALMA observations have somewhat surprisingly revealed the presence of large amounts of dust in the first generations of galaxies in the Universe. Unfortunately, their dust temperature Td remains difficult to determine due to the limited available FIR continuum data at redshift z>5. This introduces large uncertainties in several properties of high-z galaxies, namely their dust masses, infrared luminosities, and obscured fraction of Star Formation Rates (SFR). We have developed a new analytical method to constrain Td using a single continuum data point at 158 microns by combining it with the overlying CII emission. With our method, one can analyse uniquely the large number of [CII] and continuum detections at high-z provided by recent ALMA Large Programs such as REBELS and ALPINE. REBELS sources analysis allows us to extend for the first time the previously reported Td-redshift relation into the Epoch of Reionization (EoR). We find that Td increases with redshift, but more mildly than previous suggestions based on stacked SEDs fitting at z<4. We produce a new physical model that explains the increasing Td(z) trend with the decrease of gas depletion time, tdep=Mg/SFR, induced by the higher cosmological accretion rates at early times. The model also accounts for the observed Td scatter at a fixed redshift. A dust temperature increase at high-z has testable and potentially relevant implications: (a) it alleviates the problem of the uncomfortably large dust masses deduced from observations of some EoR galaxies, (b) it results in a larger obscured fraction of the SFR.

I will discuss results from my recent study of the protoplanetary disk GM Aurigae as part of the ALMA large program “Molecules with ALMA at Planet-forming Scales.” Using new and archival ALMA observations, we construct a disk physical/chemical model which reasonably reproduces the spatially resolved CO isotopologue emission, millimeter dust continuum, and the unresolved HD detection from Herschel. Our best fit model favors a large, cold protoplanetary disk with a gas mass of approximately 0.2 solar masses, a factor of 10 reduction in CO gas inside roughly 100 au and a factor of 100 reduction outside of 100 au. Despite its large mass, the disk appears to be on the whole gravitionally stable based on the derived Toomre Q parameter. However, the region between 70 and 100 au, corresponding to one of the millimeter dust rings, is close to being unstable based on the calculated Toomre Q of < 1.7.

Education and its contribution to science, technology, and innovation are the key points for combating poverty in the long term. Education is also a key point for empowering girls and women, which is fundamental for achieving the United Nations Sustainable Development Goals (SDGs). Astronomy is a powerful tool to promote education and science but, in addition to that, it is also one of the leading sciences for bringing strong technological developments and innovation. Africa has amazing potential due to natural and human resources for scientific research in astronomy. The status of astronomy and space science in Africa changed significantly over the past years, becoming emerging fields across the continent, and never before it was more possible to use astronomy for development as it is nowadays.

This talk will summarise different activities carried out for education, science, and technological development in Ethiopia, East Africa, and across the continent, and show how through them we can fight poverty in the long term, and increase in future our possibilities of attaining the United Nations Sustainable Development Goals (SDGs) for the benefit of our all society.