Seminars and Colloquia at ESO Garching and on the campus
December 2023
Abstract
Active galactic nuclei (AGN) are thought to play a key role in shaping the buildup of galaxies. If AGN influence galaxy growth, then they will reasonably impact the molecular gas reservoir first, and star formation (SF) as a consequence. Literature results concerning the gas content of high-z AGN hosts are often focused on high-luminosity AGN (log(LBol/erg/s) > 46), i.e. good candidates for driving outflows. The SUPER and KASHz surveys are sibling projects that aim at assessing AGN feedback in samples of unbiased, high-z, X-ray-selected AGN. The SUPER project recently found that significant CO depletion is present only in the most massive host galaxies (log(M*/Msun) > 11), demonstrating the importance of using unbiased samples representative of the AGN population at cosmic noon.
I will present our efforts to extend such an analysis through an expanded sample of AGN at cosmic noon, obtained by merging SUPER and KASHz targets. We carried out a comparative study of the total molecular gas content, as traced by CO, of a sizable sample of cosmic noon AGN and a matched sample of non-AGN galaxies. Applying the Bayesian framework developed by the SUPER project, we find that the properties of AGN host galaxies at cosmic noon are in general very similar to those of non-AGN galaxies, thus ruling out a strong effect of AGN feedback in this gas phase on galaxy scales. Lastly, I will report on the comparison between our observational results and the predictions of cosmological simulations.
Abstract
Despite their tiny size relative to spiral and elliptical galaxies, dwarf galaxies wield a disproportionately significant cosmological impact holding fundamental information crucial to our understanding of galaxy formation and evolution. Due of their low mass, and their elevated star formation rate, abundant gas, and low metallicity, star forming dwarf galaxies emerge as pertinent counterparts observable in the local Universe, mirroring certain characteristics of galaxies that originated in the early Universe. Due to their proximity and diverse range of gas, dust and stellar content, local universe dwarf galaxies can be thought of as individual snapshots capturing galaxies of varying ages and evolutionary stages which, when studied together can help to construct comprehensive self-consistent models elucidating the evolving properties of the interstellar medium.
In this seminar I will review what we know to date of the properties of the dust and gas in the local universe dwarf galaxies. I will highlight one of the most persistent mysteries prominently noted in dwarf galaxies: the enigmatic nature of the pervasive “dark gas” and discuss how to reconcile the rigorous star formation activity in dwarf galaxies and their scarcity of CO emission, our usual proxy for molecular gas necessary for star formation. The conversion of observed CO to total molecular hydrogen mass in low-metallicity dwarf galaxies is a formidable obstacle complicating our understanding and simulations of molecular clouds to star formation in early-universe galaxies for which our local dwarf galaxies may be useful references.
Video
Abstract
Unraveling the drivers of the observed diversity of exoplanetary systems has become one of the fundamental issues in modern astronomy, and is vital to understanding our own origins. To this end, correlations between observed exoplanet properties and stellar properties, such as metallicity and age, are important constraints on the theory of planet formation. However, a property that is unobserved for the vast majority of the known exoplanet population is emerging as an important influence on the planet formation process. This property is the star formation environment that is external to the (proto-)planetary system. In this talk I will review evidence that neighbouring stars sculpt planetary systems via stellar encounters, external photoevaporation and late-stage infall. I will also explore how these processes relate to diverse astrophysical problems, from sub-stellar objects to globular clusters. While evidence increasingly suggests that planet formation models cannot be decoupled from the physics of star formation in giant molecular clouds, the precise nature of the link between birth environment and the final planet population remains an exciting mystery.
Video
Abstract
TolTEC, a large-format (~7000 detector) imaging polarimeter, will conduct two legacy extragalactic surveys at 1.1, 1.4 and 2.0mm at the 50m Large Millimeter Telescope. The Ultra-Deep Survey of Star-forming Galaxies (~0.8 sq.deg., r.m.s. ~0.025mJy at 1.1mm) is a confusion-limited survey which ties the entire Luminous Infrared Galaxy population from redshifts 2 to 10 directly to their optical counterparts and addresses the question of how do massive galaxies build up metals and stellar mass over cosmic time. The Large Scale Structure Survey (~40-60 sq. deg., r.m.s.~0.25 mJy at 1.1mm) probes the relationships between the spatial distribution of star forming galaxies and large scale structure and provides a detailed view of clusters and their substructure via the Sunyaev-Zeldovich (SZ) effect. We show the predictions derived from cosmologically motivated simulations for these surveys and the accessibility of the community to them.
Abstract
One of the most powerful tests of our cosmological model is to verify the predicted growth of large-scale structure with time. Intriguingly, many recent measurements have reported small discrepancies in such tests of structure growth ("the S8 tension"), which could hint at systematic errors or even new physics. Motivated by this puzzling situation, I will present new determinations of cosmic structure growth using CMB gravitational lensing measurements from the Atacama Cosmology Telescope (ACT). These ACT DR6 CMB lensing measurements allow us to directly map the dark matter distribution in projection out to high redshifts; new cross-correlations of CMB lensing with unWISE galaxies also allow us to probe the matter tomographically. I will discuss the implications of our lensing results for the validity of our standard cosmological model as well as for key cosmological parameters such as the neutrino mass and Hubble constant.
Video
Abstract
Circumbinary disks are found in a variety of astrophysical scenarios, from binary star formation to supermassive black holes. The interaction and accretion from a disk can influence the orbit of the binary, either leading to circularization, or exciting the eccentricity, widening the orbit or shrinking it and facilitating mergers. I will talk about how these effects come into play and what kind of observational signatures can they leave on a population of binaries.
Abstract
I discuss how ESO instruments can advance measuring the mass functions of stellar-mass black holes and extrasolar planets. The recent success of interferometric resolution of microlensed images with VLTI-GRAVITY opens up a new venue for discovering isolated stellar remnants. GRAVITY+ will be capable of discovering a large sample of black holes and studying their distributions. Microlensing is unique at finding low-mass cold planets beyond the snow line and free-floating planets. ELT AO imaging will be able to make a breakthrough in characterizing the mass function of microlensing planets.
November 2023
Abstract
The stellar initial mass function (IMF) is central to our theoretical and observational understanding of the Universe. For decades, the IMF has been considered to be universal and our explanation for many astrophysical processes heavily relies on this assumption. However, the widely-adopted universality of the IMF is now directly challenged by detailed observations of massive early-type galaxies, where the IMF seems to systematically depart from the Milky Way standard. In this talk, I will showcase how the use of MUSE IFU data allows for an unprecedented view of the stellar population properties of nearby galaxies, and in particular of IMF variations. I will also demonstrate that the combination of detailed stellar population analysis and Schwarzschild dynamical models provides valuable information about the origin of the observed IMF variations in massive galaxies. Finally, I will describe our most recent efforts to go beyond what is currently possible with standard stellar population analyses and the promising prospects for the upcoming years.
Video
Abstract
Paper: https://www.nature.com/articles/s41566-023-01316-8
Abstract
Quasars are known for their intrinsic variability, which is stochastic at a range of timescales. Studying these objects in very large samples helps to improve the statistics and to have a systematic study of the time scales of variability, probing the relationship with the physical mechanisms driving these changes. With the upcoming large-time domain photometric surveys, we expect to discover at least a few millions of new AGN. However, detection and estimating their redshifts from photometric data presents an active research problem, and the large number of sources makes spectroscopic follow-up impossible. I will present ongoing research results on redshift estimation for these sources, taking advantage of cosmological time dilation coupled to intrinsic variability. We used MCMC iterations, effectively modeling the optical light curves of AGN by constraining the structure function and obtaining their redshift priors. I will present a validation of this method, conducted using a well-sampled light curve from the Zwicky Transient Facility (ZTF), as a proof of concept for our approach, which demonstrates that the obtained redshift priors align very well with spectroscopically determined redshift values.
Abstract
Massive stars play crucial roles in shaping the physical and chemical evolution of galaxies, influencing their environment from the early protostellar phase, where powerful jets impact the surroundings, to their violent deaths as supernovae. However, observing these stars and their immediate environments directly proves challenging due to their formation within deeply embedded parental clouds. Since accretion and ejection processes are inherently linked, protostellar outflows, which can extend several parsecs, provide crucial information about the mechanisms governing massive star formation near the central engine and unveil the elusive massive protostars. There is also mounting evidence suggesting that massive protostars may accumulate mass in episodic events, indicated by the knotty structure of jets and recent accretion burst discoveries. In this talk, I will guide you through an observational journey in massive star-forming regions, focusing on the near-infrared and data from the VLT, LBT, HST, and JWST. Additionally, I will introduce a newly developed Python package called 'sedcreator,' designed specifically for fitting spectral energy distributions for massive protostars.
Abstract
Protoplanetary disks as young as 0.5 Myr bear gaps and rings as tentative planet signposts, which aligns with accumulating evidence of early planet formation. The evolution of young disks is thus crucial to our understanding of planet formation. Early massive disks are gravitationally unstable, featuring spiral density waves. We show in global simulations that spirals can drive a large-scale dynamo, leading to near thermal field strength, even in poorly ionized disks. The strong magnetic fields will wrap up the fragment upon disk fragmentation, allowing the persistence of fragments (protoplanets) as light as Neptune. However, direct evidence of early planet formation is scarce. We suggest warps in class I/II disks are probably related to misaligned planets formed early; otherwise, warps decay quickly due to hydrodynamic instabilities.
Abstract
Scattering Amplitudes are essential building blocks to extract physical information from quantum field theory. Leveraging recent developments which allowed us to link scattering amplitudes with topics in geometry and pure mathematics, in this talk I will provide an overview of our current understanding of the general properties of scattering amplitudes and how to exploit them to investigate elusive phenomena in particle physics and related fields.
Abstract
Our Cosmic Home, which is the local volume of the Universe centered on us, contains very prominently visible structures, extending over hundreds of Mpc. Such structures, ranging from the Local Group over the Local Void and the most prominent galaxy clusters like Virgo, Perseus, Coma and many more, represent a formidable site where extremely detailed observations exist. Therefore there is a long standing effort to determine the properties of the local, large scale structure. This effort is accompanied by constructing cosmological simulations which describe the formation of these specific structures. Thereby, cosmological simulations of the formation of galaxies and galaxy clusters within the Local Universe, rather than any other, randomly selected part of the cosmic web, can be an important tool to test our formation and evolution theories of galaxies and galaxy clusters in detail. I will present results from our latest realization of such simulations to answer some key questions: How good are such simulations representing the local, large scale structure? How well can we reproduce the properties of individual galaxy clusters and their formation history? Can we start testing baryonic physics by comparing such simulations to observations?
Video
Abstract
Paper: https://arxiv.org/pdf/2306.16408.pdf
Abstract
Incredible images of astrophysical objects in printed materials and in digital form are used by professional astronomers for research and by the general public for outreach and educational purposes. However, professional astronomers and the general public alike are blind to nearly all astronomical phenomena without technological and computational aids to produce the images that we are now used to ?seeing?.
Challenging the idea that we should always use visualisations of astronomical data (i.e., graphs or images), there has been an emerging research interest over the past decade in converting astronomical data and phenomena into sound ("sonification"). Motivation for this includes the potential to enhance scientific discovery within complex datasets, by utilising the inherent multi-dimensionality of sound and the ability of our hearing to filter signals from noise. Other motivations include creating engaging multi-sensory resources, for education and public engagement, and making astronomy more accessible to people who are blind or have low vision, promoting their participation in science and related careers.
I will review the current status of the field of sonification in astronomy, and describe potential benefits of sound in the context of research, outreach, and education. I will also discuss current limitations and challenges of the approaches taken and suggest future directions to help realise the full potential of sound-based techniques when applied within the astronomy community.
Abstract
A cosmological magnetic field of nG strength on Mpc length scales could be the seed magnetic field needed to explain observed few microG large-scale galactic magnetic fields. I first briefly review the observational and theoretical motivations for such a seed field, two galactic magnetic field amplification models, and some non-inflationary seed field generation scenarios. I then discuss an inflation magnetic field generation model. I conclude by mentioning possible extensions of this model as well as potentially observable consequences.
Abstract
Substellar objects change colors as they cool, moving from the red, dusty L-type to the blue, clear T-type, as their chemistry evolves. Planets, with lower surface gravities than brown dwarfs, follow this trend, but with redder colors than the field population. This planetary L-T transition has, until now, remained unconstrained observationally, with many L-dwarfs but only a handful of late T-dwarf planets directly imaged. AF Lep b is a newly discovered planet that saddles the L-T transition and can provide a key insight into the dynamic chemistry and clouds of these atmospheres. Additionally, the planet has the lowest dynamically constrained mass of the directly imaged planets, and might have formed via core accretion.
William O. Balmer is a PhD student at the Johns Hopkins University and the Space Telescope Science Institute; they work on direct imaging and interferometry in order to understand the atmospheres of gas giant planets. They will present their team’s latest exciting observations of AF Lep b with both VLTI/GRAVITY and JWST/NIRCam, and discuss evidence that could suggest the planet formed via core accretion.
Abstract
Proteins are the workers in our body. There are many thousands of distinct proteins of complex nature each comprising thousands of atoms within a single polypeptide chain folding into specific dynamic structures to exert their function. The question to be addressed is how they started from a prebiotic soup. Another interesting question of interest is that in current life genetic information is mostly stored on DNA/RNA while the work is mostly performed by the machine proteins. Is it possible that at the origin of life information and performing function/work was both at the same entity, i.e. with proteins? We will address these questions from a physical perspective also because in contrast to simple phyisco chemical processes such as avidity and phase separation, chemical synthesis of complex molecules requires high specificity difficult to reach.
Abstract
Our current understanding of galaxy formation is based on the presence of an elusive matter component: the Cold Dark Matter (CDM). This simple model has ben challenged many times in the past decade, mainly by galaxy observations on small scales: from the abundance of satellites, to the distribution of dark matter within galaxies, and more recently by the discovery of galaxies "without" dark matter.
In my talk I will first revise all these claims with the help of cosmological numerical simulations of galaxy formation from the NIHAO project. I will then discuss whether there is indeed an observational motivated need to abandon Cold Dark Matter and move beyond such a simple model.
Video
Abstract
The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is an upcoming radio interferometer array to be located at the South African Radio Astronomy Observatory (SARAO) Square Kilometre Array (SKA) site in South Africa. HIRAX is entering into the deployment phase of the initial 256-element array of 6 metre dishes each of which will be instrumented with dual-polarisation feeds operating over a frequency range of 400-800 MHz. I will present an overview of the HIRAX instrument and science goals, focusing on the planned cosmological intensity mapping survey. Through this survey of ~15,000 square degrees of the southern sky, HIRAX aims to tomographically map the distribution of large-scale structure over the redshift range of 0.775–2.55, as traced by the 21 cm emission of neutral hydrogen. Due to the presence of strong foreground signals at low frequencies, the success of this survey relies on the careful control of calibration and systematics. I will discuss the design, instrument characterisation and analysis challenges that this presents.
Abstract
Paper: https://arxiv.org/pdf/2302.07878.pdf
Abstract
An intriguing tension in the measurements of the Hubble constant H0, which 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.
Abstract
Exoplanet research has revolutionized our understanding of planetary systems beyond our own solar system. In particular, characterizing the atmospheres of exoplanets is crucial for determining the nature of their environment and tracing their formation history. In this talk, I will explore the latest exoplanet atmospheric characterization with Hubble and JWST from the UV to the mid-IR across a wide population of exoplanets. I will discuss the challenges in analysing the observations from systematics to chance events. I will also highlight the ways we interpret the spectra to understand the chemistry and dynamics of the atmosphere. I will finish with some of the most recent discoveries and future prospects for exoplanet atmospheric characterization.
Video
Abstract
Ground-based optical astronomical observations, supported by or in the vicinity of laser guide-star systems, can be contaminated by Raman-scattered laser photons. Raman scattering is an inelastic process through which laser photons excite (vibro-) rotational modes of air molecules. In this talk, I will review the efforts undertaken to characterize this effect at the VLT: from its initial discovery via MUSE AO observations in 2016, to the recent publication of a 15.3-hr deep ESPRESSO spectrum of the 4LGSF up-link laser beams (https://ui.adsabs.harvard.edu/abs/2023PhRvR...5b3145V/abstract).
This latter spectrum was acquired as a means to 1) assemble a high-resolution, exhaustive atlas of Raman lines, and 2) assess independently the spectral accuracy of ESPRESSO. With it, we could identify 865 Raman lines over the spectral range of [3770; 7900] Å≈ [+9540; –4315] cm−1, with relative intensities spanning 5 orders of magnitudes. These lines are associated to the most abundant molecules of dry air, including their isotopes: 14N 14N, 14N 15N, 16O 16O, 16O 17O, 16O 18O, and 12C 16O 16O. These data also reveal that the four laser units of the 4LGSF do not all lase at the same central wavelength.
Altogether, our observations demonstrate that all is not "gloom and doom" when it comes to the Raman lines. If the Raman contamination of AO data remains unavoidable, the same signal stands ready to be exploited by motivated professional observatories as highly-accurate, on-sky wavelength references - and more …
Abstract
Star formation occurs in the densest parts of molecular clouds, which can be studied via molecular line emission, typically rotational transitions observed at radio wavelengths. These molecular lines provide a wealth of information about the physical condition of the interstellar medium, including the gas density, temperature and dynamics. In this blackboard presentation, I will present how turbulent models of star formation describe the density structure of molecular clouds. Based on these models, I will discuss how the properties of molecular clouds affect molecular line emission and the star formation rate. I will conclude by comparing the model predictions with observations and show that density-sensitive line ratios are powerful tracers of molecular cloud density.
Abstract
In this talk I report upon our results on the intracluster medium (ICM) of two clusters at the time when first clusters start to emerge from the cosmic web, z~2. Results are derived from new, high resolution, deep SZ and X-ray data providing us with the measurement of the two most distant resolved pressure profiles. IDCSJ1426 cluster at z=1.75 has a core whose properties are not far from the final stage, while the remaining part of the cluster is experiencing a sizable gas, heat and entropy transfer. JKCS041 at z=1.80 is caught just after a major merger event as evidenced by its SZ-X-ray peak offset, its low central pressure, and its low Compton-Y parameter compared to its WL mass. Comparison with plausible descendents shows that its ICM will experience major changes at all radii.
Abstract
In the past decade many population studies have been performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to understand the bulk properties of protoplanetary disks around young stars. These population studies mostly consist of late spectral type (i.e., G, K & M) stars, with relatively few of the more massive Herbig stars (spectral types B, A, F).
With GAIA updated distances, now is a good time to use ALMA archival data to do a Herbig disk population study, an important step towards understanding planet formation. For a significant fraction of all known Herbig disks up to Orion, ALMA Band 6 or 7 archival data is available to determine the dust and gas masses and sizes. In this talk I will show how Herbig disk dust and gas masses compare to T Tauri disks. We find that Herbig disks are skewed towards higher dust masses and larger radial extents compared to the disk populations of Lupus and Upper Sco. Additionally, using the thermochemical code DALI, we find that the gas masses based on CO isotopologue observations are consistent with an ISM gas-to-dust ratio of 100, in contrast to T Tauri disks for which lower gas-to-dust ratios are found. Herbig disks are massive: both the dust and the C18O gas are likely optically thick, so we need to go towards rarer isotopologues to obtain direct measurements of the bulk disk mass. Finally, I will go into differences within the Herbig disk population and I will show what one can expect for future Herbig disk research.
Abstract
Nuclei and hadrons are “laboratories” for exploring nature’s fundamental interactions. In this talk, I discuss the theoretical challenges and advances in the interpretation of experimental tests of fundamental symmetries performed with these strongly interacting systems. This theoretical work has enabled us to exploit such tests to achieve a deeper understanding of the dynamics of Quantum Chromodynamics in the non-perturbative regime and to gain a powerful new tool in the hunt for possible physics beyond the Standard Model.
Abstract
What is the origin of magnetism on large cosmic scales? How are cosmic rays accelerated and how do they move through the cosmos? What are their effects on structures such as galaxies? These are the questions we explore in this talk.
Recent advances in radio observations have shed new light on the cosmic ray and magnetic field distributions in the Universe, from the circumgalactic medium all the way to cluster of galaxies and cosmic voids. Cosmic rays play a crucial role in driving galactic winds, which, in turn, play a key role in galaxy evolution and the evolution of baryons. Radio observations are also an extinction-free tracer of star formation and provides unique insights into the transport mechanism of cosmic rays.
Using polarisation observations of LOFAR and MeerKAT, we have been able to extract the very first profiles of magnetic fields around nearby and distant star-burst galaxies.
Radio observations have also revealed magnetic fields in cosmic filaments of galaxies. In combination with cosmological simulations, we can derive constraints on the origin of cosmic magnetism. Low-frequency radio observations have shown that clusters of galaxies can host huge reservoirs of cosmic rays, in a phenomenon that we have called megahalos.
Video
October 2023
Abstract
For a proper understanding of the evolution of high-redshift galaxy clusters, it is necessary to consider both passive and star-forming galaxies. Because of the cost associated with spectroscopy over a large field of view, alternative searches based on candidate colors are suggested. To distinguish passive galaxies from star-forming ones, additional color constraints are required. Based on imaging of 64 high-redshift radio AGN (1 < z < 2) using Spitzer, Herschel, the Hubble Space Telescope, and other ground-based facilities, about 40 young clusters have been identified. The redshift of the clusters, which is the radio AGN, is known, and the candidate cluster galaxies have been deduced using color criteria. The presence of red overdensities (within a 250 kpc radius) confirms the cluster formation. However, the red galaxies display a wide range of colors, some of which exhibit a rest-frame UV excess. In certain clusters, there is an inner concentration of blue galaxies, indicating active star formation even at the core of the clusters. The derived number of central luminous red galaxies and the radial density profiles are comparable to those found in local clusters, indicating that some 3C clusters are already mass-rich and compact.
Abstract
The current view of the local Milky Way is in crisis. Data from the ESA Gaia mission has overthrown the 150-year-old paradigm for the organization of the star-forming gas in the local neighborhood and the structure of stellar clusters and associations. In the new view, local star-forming regions are connected by lower-density gas and are part of a new organizational unit: undulating, coherent, and narrow Galactic-scale gas structures. While these new structures are likely associated with spiral arms, they do not fit the current model of the Milky Way. Open stellar clusters are far from the round stellar structures we thought they were, and instead have long, cigar-shaped coronae surrounding them. The once clear line between stellar cluster and stellar association is fading, if there at all. In this talk, I will present the new paradigm and the challenges and opportunities it poses to our understanding of the Milky Way and star and planet formation. I will also present the preliminary results from ESO Public Survey VISIONS, a large observational effort to map the local gas in the NIR focusing on a series of ISM and star formation topics, including making the first measurement of the 3D space motion of interstellar gas and construct a spatio-temporal atlas of the local gas. I will end with early results on "Galactic Weather", meaning, the currently unknown relation between mass extinction or climate change events on Earth and the Sun's crossing of dense clouds and spiral arms, made possible by our preliminary measurements of the ISM 3D motion.
Abstract
Galaxy clusters are an important cosmological probe, tracing both the growth of structures and the expansion history of the Universe. The population of distant (z>1) clusters remains poorly known, due to the limited sensitivity of present telescopes. In X-rays, the ATHENA mission is a promising observatory to detect large numbers of these early massive objects. During this informal discussion, I will introduce cluster number counts cosmology, present the capacities of ATHENA regarding high-z cluster detection, and discuss how it could help cosmology in the 2030s.
Abstract
High-resolution ALMA observations have opened a new window to study galaxy dynamics at z>1, using cold gas tracers such as CO, [CI], and [CII] emission lines. In this talk, I will present recent results on cold gas dynamics in high-z galaxies, focusing in particular on the ALMA TRICEPS survey of massive galaxies at z=4-5. In all the observed galaxies, the cold gas forms dynamically-cold rotation-supported disks, indicating that regular rotation is ubiquitous in massive systems up to z=5. In several cases, the galaxy rotation curve requires the presence of a central mass concentration (a stellar bulge) in addition to a pure exponential disk. Overall, the ALMA data suggest that massive galaxies must have formed and evolved surprisingly fast during the first billion years of the Universe's lifetime.
Abstract
Stars form in the coldest and densest phases of the interstellar medium, where gas is mostly in molecular form. Molecular transitions at radio and microwave wavelengths, hence, represent the ideal diagnostic tool to probe these regions. I will show how through their analysis we can infer the physical and chemical structure of star-forming regions, in order to understand how they evolve. I will showcase examples of the power of this technique in both the low- and the high-mass regimes, addressing in particular the gas ionisation state and its kinematic properties. I will conclude with a few remarks on the future perspectives for galactic star formation.
Abstract
The Large Fiber Array Spectroscopy Telescope (LFAST) will combine thousands of small "unit telescopes" to create an array with collecting area greater than that of the GMT, TMT, or E-ELT, but at a fraction of the cost of those facilities. Light from an astronomical source will be combined incoherently using optical fibers to illuminate one or more high-resolution spectrometers. LFAST is aimed at problems that require spectra with extremely high signal-to-noise, such as the detection of biosignatures in the atmospheres of Earth-like exoplanets, or faint targets that benefit from high-resolution spectra. Each unit telescope is comprised of: a 1" thick, 30" diameter spherical primary mirror on a support with tip-tilt actuators for alignment and focus; a refractive prime focus corrector (PFC) that corrects spherical aberration over an 8 arcmin field; a fiber at prime focus that subtends 1.4 arcsec; and a guide camera fed by an optical relay to provide feedback for pointing correction. The LFAST concept combines 20 unit telescopes in a common frame on a single alt-az mount. The system is being designed to operate outdoors without the protection of a dome. As of summer 2023, the LFAST team has constructed a prototype unit-telescope on a dedicated mount, and are testing its performance on sky. In this talk, I will describe the LFAST concept and current the status of the unit telescope tests, and development of the 20 unit prototype. I will present our latest progress in fabrication of the primary mirrors, PFC and guider optics, and the 20 unit frame.
Abstract
We used more than 25 million galaxies in the Subaru Hyper Suprime-Cam (HSC) shear catalog in the redshift range up to z~1.5 to measure weak lensing distortion effects due to large-scale structures. We used the measured weak lensing signals to perform a blinded cosmology analysis to measure the cosmological parameters of the flat LambdaCDM model. To obtain a robust constraint on the cosmological parameters, we employed a uninformative flat prior to model a possible residual systematic error in the mean redshift for HSC galaxies at z>1. As a result, we were able to measure the “S8” parameter at a 4% accuracy (sigma(S8)~0.04), but the central value exhibits about 2.5sigma tension with the Planck inferred S8 value. Our results indicate a non-zero residual error in the mean source redshift compared to the photometric redshift estimates for the HSC galaxies at z>1. In this talk, I will discuss the HSC cosmology results, and, if time is allowed, present the current status of the upcoming Subaru Prime Focus Spectrograph project, which promises significantly improvement of the HSC cosmology results.
Video
Abstract
Evolutionary scenarios predict that obscured quasars play a key role in the evolution of galaxies; however, this role has not yet been fully understood since quasar samples are typically biased against obscured systems. We select and constrain the AGN and host galaxy properties of a complete and unbiased sample of 578 infrared (IR) quasars (𝐿AGN,IR>1e45erg/s) at 𝑧<3, using spectral and photometric data from X-rays to radio wavelengths. We find that 61% IR quasars are obscured (55% are X-ray undetected) and identify fundamental differences in the average properties of obscured and unobscured quasars: 1) obscured quasars have star-formation rates ≈3 times higher, driven by a larger population of extreme starburst host galaxies, 2) obscured quasars have stronger radio emission, potentially due to the interaction of jets or winds with a higher opacity circumnuclear medium (i.e., quasar “feedback”), and 3) obscured quasars cluster significantly more strongly than their unobscured counterparts. The suppression of star formation in unobscured quasars is potentially caused by the interaction between jets or winds with the interstellar medium, which can blow out the star-forming gas. We find that many of the obscured quasars are sub-mm galaxies and show that part of the obscuration can be due to compact dusty starbursts in the most extreme cases. We will also present and show our predictions for our 4MOST IR AGN survey, which will target ~200000 obscured quasars. We will discuss the role of obscured quasars in the evolution of galaxies, and how future facilities will help to improve understanding of this topic.
Abstract
The circumgalactic medium (CGM) is a crucial component of galaxy evolution, but thus far its physical properties are highly unconstrained. As of yet, no cosmological simulation has reached convergence when it comes to constraining the cold and dense gas fraction of the CGM. Such components are also challenging to observe, as they require sub-millimeter instruments with a high sensitivity to extended and mostly diffuse emission.
We present a state-of-the-art theoretical effort at modeling the [CII]158 micron, [CI](1-0)609 micron, [CI](2-1)370 micron, CO(3-2)867micron, and [OIII]88 micron line emissions that arise from the ISM and CGM of galaxies. We use the high-resolution cosmological zoom-in simulation Ponos, which represents a typical star forming galaxy system at z = 6.5, composed of a main disc with stellar mass M_stellar = 2 *10**9 M_sol, that is undergoing a major merger. We adopt different modeling approaches based on the photoionisation code Cloudy. Our fiducial model uses radiative transfer post-processing with RamsesRT and Krome (KramsesRT) to create more realistic FUV radiation fields, which we then compare to other sub-grid modeling approaches adopted in the literature.
We find significant differences in the luminosity and in the contribution of different gas phases and galaxy components between the different modeling approaches.
[CII] is the least model-dependant gas tracer, while [CI](1-0) and CO(3-2) are very model-sensitive. In all models, we find a significant contribution to the emission of [CII] (up to ~10%) and [OIII] (up to ~20%) from the CGM. Our fiducial RT model produces a lower density, T ~ 10**4 K tail of [CII] emission that is not seen in the other more simplistic models and that resides entirely in the CGM. Notably, [CII] and [OIII] trace different regions of the CGM: [CII] arises from an accreting filament and from the tidal tails connecting the main disc and its merging satellites, while [OIII] traces a puffy halo surrounding the main disc, probably linked to supernova feedback.
We discuss our results in the context of sub-millimetric observations, highlighting the limitations of ALMA for observing the cold ISM and CGM from sources that have a large angular extent on the sky.
This project is part of the ongoing efforts at producing theoretical predictions for future submm observations with AtLAST and is funded by the AtLAST EU grant.
Abstract
Massive stars play crucial roles throughout the universe, especially via their radiative, mechanical and chemical feedback on their surroundings. Since most stars, including massive ones, appear to form from giant molecular clouds (GMCs) in the form of star clusters and associations, understanding this process is key for a more complete picture of the evolution of galaxies, stellar populations and planetary systems. Here I discuss some recent projects studying the lifetime and evolution of GMCs, the role of turbulence, magnetic fields and cloud collisions in setting initial conditions for star formation, and latest observational tests of theoretical models of massive star and cluster formation, including with VLA, GBT, ALMA, SOFIA, LBT and JWST.
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Over the last two decades the important of binaries in understanding stellar populations has become widely recognized. However, the physics of interactions in binary stars has many open questions and uncertainties. In this talk I will outline how we can use electromagnetic and gravitational wave observations across cosmic history to constrain these uncertainties. I will focus on recent results from the Binary Population and Spectral Synthesis (BPASS) code. Showing that because BPASS differs from other similar codes in the treatment of binary interactions we can gain new insights into the physical processes of binaries. With these results allowing us to understand, stars, galaxies and the Universe with greater accuracy.
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September 2023
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Over the past 20 years it has become increasingly clear that supermassive black holes are essential components of galaxies, as demonstrated by the correlations connecting black hole masses and large-scale galaxy properties. Although about ~100 dynamical black hole mass measurements have been made to date, the local black hole mass census is highly incomplete. Gaining a more complete picture of black hole demographics and a deeper understanding of the mechanisms that drive black hole - galaxy co-evolution requires the measurement of black holes in a wider range of galaxies with diverse evolutionary histories. I will discuss several recent and on-going programs aimed at taking this necessary step, as well as the observational and modeling advances that have made the work possible.
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I will give a brief summary of my science interests, including galaxy structure and morphology, stellar kinematics and stellar populations, the effect of internal galaxy structures (bars/bulges etc) on their host galaxy evolution, and disc assembly histories. Then, I will tell you all about two exciting new ESO/VLT large programmes that I am heavily involved in, GECKOS and MAUVE, and share some of our very first results.
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I will discuss an HR diagram and chi2 map from a multi-data analysis of a triple star. One of the components is very offset from a normal position. This is either related to its log g value or to its mass. However, both values are well constrained by observations. I would welcome your comments and ideas.
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CO is one of the most abundant molecules in protoplanetary disks, and optically thin emission from its isotopologues has been detected in many of them. In this talk, I will discuss a new comprehensive model that considers the most important attributes relating to CO: (a) isotope-selective chemistry, (b) freeze-out with considering the grain-surface chemistry, and (c) gas density and temperature structures that are both consistent with the thermal pressure gradient. From this model, the CO as well as CI line emission support large masses around large Myr-old disks. I will also present a simplified model that is capable of detailed modeling of individual targets, and its application to the disk of RU Lup. We find a disk mass larger than the Minimum Mass Solar Nebula, whereas previous estimates were around a Jupiter mass. The simplified model has been released to the community (Python-Fortran code DiskMINT: Disk Model for INdividual Targets), so that the community can extend this approach to other disks.
Abstract
Recent advancements in distance measurement techniques have unveiled discrepancies in the estimation of the Hubble parameter between early and late Universe indicators. Additionally, non-negligible disagreements have emerged in the Hubble parameter values derived from near-Universe indicators, such as Cepheids and the Tip of the Red Giant Branch (TRGB). Thus, the establishment of new, independent, and reliable distance estimation methods provides an important sanity check.
In this context, Type II supernovae have remained an underutilized resource. Their relatively straightforward physics, combined with recent advancements in modelling techniques, make it possible to estimate precise distances without relying on the calibration ladder. Apart from describing the potential of Type II supernovae as a dependable distance measurement tool, I will also showcase it by presenting the results of two recent empirical tests:
- Internal Consistency Assessment: I will discuss the application of this method to a sample of Type II supernova siblings, aiming to assess the internal consistency of the technique (Csörnyei et al. 2023a, https://ui.adsabs.harvard.edu/abs/2023A%26A...672A.129C/abstract
- Direct Comparison with Cepheid and TRGB Distances: I will alsopresent a direct comparison between Type II supernova distance estimates and those derived from Cepheid and TRGB measurements, using the case study of Messier 51 (Csörnyei et al. 2023b, https://ui.adsabs.harvard.edu/abs/2023arXiv230513943C/abstract.
Both of these initial tests yield encouraging results, showing that obtaining a high-precision value for H0 through Type II supernovae alone is indeed possible.
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We use the oldest stars born in-situ in the Milky Way to study its chaotic and turbulent pre-disk state that we dub Aurora. Through the chemo-kinematic analysis of the local stars we reveal the Galactic spin-up, i.e. the emergence of the Milky Way's stellar disk. The Galaxy's transition from Aurora to a stable and dominant disk is accompanied by a variety of additional phenomena: i) a marked drop in the fraction of star formation locked in massive star clusters, ii) a large reduction in elemental abundance spread, and iii) a change in the slope of the stellar metallicity distribution.
We compare the observed properties of the high-redshift Milky Way to the results of numerical simulations of galaxy formation and discuss the implications of our study.
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Galaxies at high-z show a morphology different from local ones. They consist of turbulent disky structures dominated by bright blue knots, dubbed clumps. The investigation of the physical properties of galactic substructures and individual clumps hosted by high-z galaxies down to the smallest scales gives unique hints to study galaxy evolution. One of the most important quantities exploited to characterize young stellar populations is the UV-continuum slope.
I will talk about the UV-continuum slopes measured for a sample of 166 individual star-forming clumps, belonging to 67 galaxies strongly lensed by the cluster of galaxies MACSJ0416. I will compare our novel measurements for individual clumps with those for integrated galaxies, in order to investigate possible physical differences between these regions and their hosts.
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Since 2018, ESO Supernova has been presenting to the public how science and cutting-edge engineering can help unravel the secrets of the Universe. An education programme is running that attracts almost 6000 children (K-12)every year. Despite being in Garching, we welcomed educators and teachers from almost all member states so far. The interest in support in education is increasing in Chile as well because of ESO’s presence there. A visit of ESO’s education coordinator to Santiago and most of the telescope sites was intended to find out, how parts of the education programme can be made accessible to the Chilean community, what the local needs are and how the ESO Department of Communication in Vitacura can be supported to establish some of the programmes developed at ESO Supernova. This talk will give an overview of this visit and the discussions with local education institutions. It’ll encourage further discussions on how the Chilean community can benefit from ESO’s work in education.
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I will review a decade-long journey in finding confirmation for a fundamental process long predicted to happen in protoplanetary disks: the migration of icy pebbles from the outer cold disk regions that should deliver water to the inner rocky planet forming region. After crossing the snowline, ice should sublimate and enrich the inner disk in water vapor that could be observed from infrared spectra. I will present evidence that has emerged from Spitzer-IRS and higher-resolution ground-based spectra in the past decade, what is now emerging from new JWST-MIRI spectra in Cycle 1, and some exciting prospects for studying rocky planet formation with JWST.
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We map the emission from the intergalactic medium and circumgalactic medium based on the extremely deep MUSE observations on the Hubble Ultra Deep Field. Spanning physical scales from a few tens to hundreds of kiloparsecs, our observations uncover varying physical processes at different proximities to galaxies. Key findings include: (1) an anisotropic MgII emission within 15 kpc around z~1 galaxies provides compelling evidence for bi-polar galactic outflows. We demonstrate that these cool, metal-enriched outflows are prevalent among massive galaxies. (2) In the case of Lyα emitters within the redshift range of 3<z<4, an average blueshift in the Lyα line extending up to 70 kpc from the galaxy suggests the existence of large-scale gas inflows. (3) We have also detected extended Lyα emission reaching out to approximately 270 kpc, marking a significant advancement in our understanding of these regions. This talk will end by previewing our ongoing efforts to reproduce the observed surface brightness and kinematic characteristics of Lyα haloes through simulations.
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We will present a short overview of ASTRON’s LOFAR telescope, the data transport in the system and the correlator back-end. ASTRON is contributing to a feasibility study for a GPU based correlator for ALMA, we will share the study goals and challenges faced and will take a deeper look at the data transport between the front-end and back-end of a radio telescope.
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In this presentation, I will present the latest findings derived from the SERRA suite, a set of cosmological simulations zooming in on high-z galaxies, spanning from the Epoch of Reionization to the Cosmic High Noon. The discussion will address two particular questions: 1) Why are the super-early (z>10) galaxies identified with JWST dim in ALMA FIR observations? 2) Do cosmological simulations predict the presence of dynamically cold disk galaxies, marked by substantial rotational support, as observed with ALMA? How will JWST/NIRSpec observations enrich our understanding of these intriguing galaxies?
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I will talk about my recent work on protostellar multiplicity and comparison with observations of a bimodal separation distribution. We find that Core fragmentation is able to reproduce observations, suggesting that core-fragmentation and migration is a likely formation pathway for binaries with separations down to 20AU. I will also talk about how binarity can complicate interpretations of observations of binary simulations. Finally, I will talk about the preliminary work on how protostars get their spin, and whether multiplicity can be a formation path for fast rotators. Our results find that fragmentation events in a circumstellar disc can lead to the spin-up of the primary star.
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Massive binaries are relatively rare systems in our universe and our understanding of the physics governing their evolution remains limited. Mass transfer events within these binaries can induce significant alterations in their structure, potentially resulting in the formation of close binary black holes or neutron stars. These binaries, in turn, are sources of observable gravitational waves. Alternatively, mass transfer events can hypothetically give rise to esoteric objects such as Thorne-Zytkow objects and Quasi stars, which are hybrid stars consisting of either a neutron star or black hole at the core of a non-degenerate star. This talk offers an overview of the various pathways through which massive binaries can transform and explores key determinants of their evolutionary outcomes, including radial expansion and the role of convection within stellar envelopes.
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With the completion of ALMA, we now have unparalleled spatial resolution at submm wavelengths, enabling detailed kinematic studies of z > 4 galaxies for the first time. In this presentation, I will show kinematic models of four galaxies at z ~ 4.5, with some of the most spatially resolved observations in [CII] using ALMA. Our findings indicate that each of these galaxies features a regularly rotating disc, and their gas velocity dispersions are significantly lower than predicted by current cosmological hydrodynamical simulations. By decomposing the rotation curves into the different mass components, we derive properties of both the dark matter halo and baryons within the inner 3 to 5 kpc. Aditionally, by analysing the velocity dispersion in the discs, we find that the gas turbulence is likely driven by the intense stellar feedback, without the need for gravitational instabilities. Furthermore, we contextualise these galaxies within the baryonic Tully-Fisher relation, exploring potential evolutionary links to local elliptical galaxies. Our findings show that cold discs can form earlier than previously thought and suggest that stellar feedback is at play to control the gas turbulence.
August 2023
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Radially pulsating stars have thew key advantage to be very accurate distance indicators and fundamental stellar tracers. We will focus our attention on the metallicity distribution (iron, alpha elements; high resolution optical spectra) of young (classical Cepheids, t<= 300 Myrs) and old (RR Lyrae, t=> 10 Gyr) stellar tracers located in the Galactic thin disk and in the Galactic Halo. We outline the role that accurate individual age estimates and kinematics (Gaia) play in constraining the chemical enrichement history of the Galactic spheroid. Finally, we outline possible avenues concerning the use of photometric indices to constrain the metallicity distribution of radially pulsating stars in nearby stellar systems.
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ALMA has revealed a number of substructures in protoplanetary disks such as rings, gaps, and asymmetries. A number of spatially resolved targets has been increasing especially owing to large programs such as DSHARP or eDisk. Such programs manly target bright (and in many cases, large) disks, and are good probe of structures at ~30au region from the central star, corresponding to Neptune-forming regions. The structures at ~10au or less, which corresponds to Earth or Jupiter regions in the Solar System are still left less explored due to the lack of spatial resolution. In this talk, we present our recent attempt to obtain structures that are formally smaller scale than the "beam size" obtained in CLEAN methods. We present some results obtained by sparse modeling and visibility analyses without any prior. We also plan to discuss a possible method to extend the visibility modeling to non-axisymmetric structures.
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Telescopes such as ALMA are purpose-built to observe at generational resolution and sensitivity – the software used to process and analyze these data must be no different. In this talk I will first motivate why the CLEAN imaging algorithm does not leverage the highest resolution and sensitivity information in ALMA datasets, then discuss two modern alternatives designed specifically to perform imaging more accurately, quickly and autonomously. Using ALMA observations of protoplanetary disks, I will show how these two open-source codes use statistical modeling frameworks to simultaneously achieve higher resolution and sensitivity than CLEAN in 1D or 2D image reconstruction. Finally I will demonstrate the new science these tools are driving in the protoplanetary disk field, including the statistical inference made possible by self-consistently imaging hundreds of datasets at high fidelity.
July 2023
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The inner regions of the Milky Way contain a significant population of old, metal-rich stars, consistent with having formed in an early high rate of star formation, within a deep potential well to allow for rapid self-enrichment. Simulations of Milky Way-like galaxies in standard LambdaCDM models fail to reach such high metallicities at early epochs, posssibly reflecting the low-mass sub-structures in which the ancient stars are predicted to form. I will quantify this comparison between observations and predictions, using available ages and metallicities for stars in our Galaxy and public datasets from two suites of simulations of Milky Way-mass galaxies. I will then interpret the results in the context of other indications of the rapid growth of Milky Way-like galaxies and their associated dark matter haloes.
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Strong large-scale magnetic fields play a crucial role in powering the central engine of high-energy astrophysical sources, which invariably require a central accreting compact object as main ingredient.
However, whether we consider the formation of a proto‐neutron star during the gravitational collapse of a massive star or the accretion disk around a supermassive black hole, it is still not well understood how such fields can be amplified to the point where they can extract rotational energy from the accreting compact object and launch the powerful outflows that we can observe.
Numerical models are an invaluable tool to study the complex dynamics of these astrophysical systems, but despite the enormous increase in computational power currently available, the large separation between all the relevant scales (e.g. plasma kinetic scale, compact object's size, jet and emission site) represents a hard challenge that astrophysical simulations still need to face.
In this informal discussion I will present some recent results on large-scale magnetic field amplification and dissipation in accreting compact objects, from their "infancy" (i.e. the proto-neutron star phase after the gravitational collapse of a massive star) to the case of black hole-accretion disk systems and relativistic jets.
I will highlight similarities and differences between these different sources, and present some of the msot recent analytical and numerical tools currently employed to address the impact of magnetic fields on the dynamics of compact objects.
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The Dark Energy Spectroscopic Instrument (DESI) is currently in its 3rd year of operation and just made public its first data release: the data from the period of Survey Validation. Located at Kitt Peak National Observatory, this multi-object spectrograph is putting together the largest 3D map of the observable universe created to date. I will give a status update on the DESI project, present the Early Data Release as well as give an overview of the early science results.
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Protoplanetary disks represent the evolutionary link between molecular clouds and planets. Knowledge of their molecular inventory is the key to unveil the chemical trail leading to life, yet too few observational constraints of disks exist at infrared wavelengths. This wavelength regime enables to study the solid and gas reservoirs of inner disks where terrestrial planets and sub-Neptunes form. Compared to previous IR facilities, the JWST MIRI instrument offers unprecedented sensitivity, spatial resolution (R=3400-1600), and spectral coverage (5-28 µm). In this occasion, I will present the first MIRI MRS observations of the PDS 70 planet-forming disk as part of the MIRI Mid-INfrared Disk Survey (MINDS; PI: Th. Henning). The much higher spectral resolution of MIRI MRS compared with previous Spitzer spectroscopy (R=100, 600) reveals emission of water vapour. This demonstrates that the terrestrial planet-forming zone of PDS 70 has maintained to some degree the physical and chemical conditions of young disks, in spite of the 54 au planet-induced gap.
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The 21st century will see a transformation in astronomy’s ground-based capabilities. ALMA is operational and a major upgrade is being planned, ELT and SKA are under construction, CTA is in the advanced planning stage and through LIGO/VIRGO/ET and IceCube, multi-messenger astronomy has landed with a bang. I will provide ESO colleagues with an update on SKAO’s status as both the Observatory and the telescopes grow; I’ll touch on the key science areas and show recent advances from SKA’s pathfinder and precursor facilities.
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The analysis of stellar populations is a very important part of understanding galaxy formation and evolution. While in nearby galaxies this can be done through the study of individual stars, at larger distances, discrete tracers become crucial tools that allow us to map the properties of stellar populations where individual stars cannot be resolved or detected. In this talk, I will introduce the two main types of discrete tracers, globular clusters and planetary nebulae, and I will give an overview of the ways in which we can use them to uncover the properties of halos.
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The outer Galaxy was believed to be an environment not optimal for the formation of complex molecules and planetesimals because the metallicity is too low, and thus excluded from the so-called Galactic Habitable Zone. However, with the advent of sensitive telescopes, we realized that the presence of small, terrestrial planets is independent of metallicity, and that molecules, including complex ones, are also abundant in star-forming regions of the outer Galaxy too. Nevertheless, their formation and survival could be different from the ones in the inner or local Galaxy due to the very different environmental conditions.
I will present the first results of the observational project "chemical complexity in star-forming regions of the outer Galaxy" (CHEMOUT). The goal of this project is to unveil the chemical composition of star-forming regions in the outer Galaxy to investigate the dominant species as a function of the Galactocentric distance. The 35 targets of our sample have Galactocentric distances in between 9 and 23 kpc. We report the detection with the IRAM-30m telescope of several carbon-bearing molecules, including the complex species CH3CCH and CH3OH. We also detect D- and 15N-bearing species, as well as tracers of protostellar activity such as SiO and SO.
The main results obtained so far, and published in three papers, are:
(1) the abundance of the studied species, including methanol, do not vary significantly with the Galactocentric distance;
(2) the protostellar activity is not inhibited even at the far-outer edge of the Galaxy;
(3) the 14N/15N ratio shows a trend with the Galactocentric distance consistent with up-to-date Chemical Evolution models of the Milky Way.
I will also show ALMA maps of several organics towards the source WB89-670, a dense star-forming core located at ~23.5 kpc from the Galactic center, where the C/O ratio is at least two times lower than Solar. Moreover, based on our results, we support previous claims that the definition of Galactic Habitable Zone should be rediscussed in view of the ubiquitous efficiency of the interstellar medium in forming organic molecules.
Abstract
What do the Pleiades have to do with a school of sardines? How can habitat exist in a computer?
These kind of conundra arise when a passionate zoologist talks to passionate astrophysicists and their very bizarre discussions get transformed and catalyzed by the expert and talented digital hand of an illustrator.
Under the premise of Baba Dioum "In the end we will conserve only what we love, we will love only what we understand, and we will understand only what we are taught", a few years ago, a group of five women embarked in a project in Valparaiso to make the general public get to know and fall in love with pairs of "astro" and "marine" "beasts". With a wink to the great "Bestiario del Reyno de Chile" illustrated book, and another one to the "memory game", the project translated in a beautifully illustrated book with key and curious facts about the wonderful "creatures" that "populate" the media above and below the coastal horizon.
In this informal talk I will present a bit of the process of this book and its inspiring illustrations.
Abstract
The aim of this lunch talk is to present the integration procedure developed at the Osservatorio Astronomico di Brera (INAF). It consists in the geometrical measurement of the as-built optical and mechanical elements with a Coordinate Measurement Machine (CMM) followed by their integration at the nominal position. A software based on a set of measurements performed on the machine itself has been developed to estimate the accuracy in terms of both geometrical values and optical effects. The obtained results have been compared and verified with a dummy system alignment. To estimate the damage on the optical elements due to the measurement operation, the forces applied by different measuring machines (Articulated Arm CMM, CMM, and Laser Tracker) have been evaluated using a strain gauge system. Starting from those data, different optical materials and coatings have been tested impinging them with a CMM and measuring the damaged surfaces with a Micro Finishing Topographer. Starting from the optical design it is now possible to define the optimal mechanical design and to choose the best alignment strategy matching the requirements in terms of optical quality, throughput loss, and stray light. The optomechanical mounts and the correction systems have been built, and their performances tested on a dummy system and on actual instruments (ESPRESSO, SOXS, and MAVIS in the future).
Abstract
The chronicle to be relayed may appear unbelievable but was carefully researched. The story was written by brilliant scientists and violent potentates over two centuries and across large parts of Europe and North America. It consists of several strands that will be woven from threads as seemingly incoherent as the following examples:
- a penniless child that bought a glass-polishing machine from money given to him after he had been rescued from a collapsed house;
- an Italian Jesuit and observatory director, who was curious about the composition of stars and discovered the circumstellar matter surrounding the object of the talk;
- effects that WWII had on the sociology of science;
- one of the last mysteries of naked-eye astronomy;
- observations made amidst exploding bombs;
- the second most important astronomy family dynasty;
- a ‘law’ that is still valid after nearly a century but already in the year following its proclamation was dramatically violated by the prototype of the stars it had been established for;
- a second unlawful star that led a whole field of research into a temporary dead end;
- a daring interpretation of decades-old observations that is still wanting a physical basis;
- astronomers who had to flee their home countries to escape from military and political threats;
- long series of careful measurements by passionate to desperate observers, who did not understand what they were seeing but refrained from adding undue speculations;
- restrictions that a very persuasive but merely empirical ‘law’ can impose on scientific thinking;
- an astronomer who rose from a peon in the streets of a megapolis in an Asian country to president of the IAU;
- the technology that enabled a science-driven entrepreneur to build a first extremely large telescope;
- efforts supported by an American lawyer to obtain a copy of an 80-year-old PhD thesis from a library in London;
- a famous female astronomer, who suffered many times from gender discrimination but called another female astronomer a man;
- a subtle mistake in the description of observations that let an ingenious ansatz fall short of the full explanation;
- a refractor that broke two observers’ legs;
- an observatory that was founded because an imperialist wanted to have accurate maps of the territories he had conquered;
- some of the last observations made at an observatory later looted by an occupation army.
The red thread onto which all these beads will be stringed is provided by a naked-eye star that has showcased itself on a dynamically evolving pedestal sculptured by physicists, chemists, glass cutters, opticians, spectroscopists, astronomers, inventors, etc. The story started and found its current end in the Munich area.
(It seems that the above information does not [yet] enable ChatGPT to identify the star.)
Abstract
The exoplanet system around the low-mass star (0.09 solar) TRAPPIST-1 is perhaps the most iconic example of a compact, multi-planet system. The planets are found at close distances from the star (but some at moderate irradiation levels) and are all in mean motion resonances. Recently, modelling of transit timings variations and photometry have resulted in unprecedented constraints on the planets masses, compositions, and their dynamical state in terms of Laplace resonance angles. These constraints offer an opportunity to inform us how the system assembled. I will present numerical simulations that reproduce the physical and dynamical properties of the TRAPPIST planets. It is found that the latter is only possible in a formation context, that is, the present dynamical state of the TRAPPIST-1 system had already been established in its first few million years.
June 2023
Abstract
Pushing the Hubble Space Telescope to its limits at the end of the last decade has allowed astronomers to view the tip of the cosmic iceberg at a time only 500 Myr after the Big Bang. While a few candidate galaxies were found, significant questions about the onset and evolution of the earliest galaxies persisted. The launch of JWST has opened up this epoch to direct and detailed observation by providing a significant leap in our ability to study the entire epoch of reionization due to its redder sensitivity and spectroscopic capabilities. The Cosmic Evolution Early Release Science (CEERS) and Next Generation Deep Extragalactic Exploratory Probe (NGDEEP) programs have enabled one of our first looks into this epoch, finding that galaxies at z > 9 are more abundant than predicted by most simulations. This hints at not only an early onset of galaxy formation, but that stars are forming differently at these early times (at higher efficiency and/or with different initial mass functions). The CEERS spectroscopic program has shown that photometric redshifts *work*, with a high fraction of spectroscopic confirmations, and only one (interesting, yet rare) case of contamination. These data have also significantly improve our ability to identify early growing supermassive black holes, showing that they appear (relatively) frequently at high-redshift, including a remarkable AGN at z=8.7. These observations pushing models of early black hole growth, implying that massive seeds and/or super-Eddington accretion are needed at early times.
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Understanding the physical and chemical properties of the interstellar medium (ISM) and circumgalactic medium (CGM) of nearby and distant galaxies is crucial to understanding galaxy evolution. We describe our studies of the gas in star-forming galaxiesat redshifts 0.02<z<0.14, based on HST COS, SDSS, and GBT spectroscopy of background quasars located within impact parameters of 1-7 kpc from the galaxies, and in galaxies at redshifts 0.2 < z < 1.4 based on HST imaging and VLT MUSE integral field spectroscopy.Combining our sample with the literature, we find the H I column density to be anticorrelated with impact parameter and stellar mass. We also find that the SFR correlates well with the stellar mass, consistent with the star formation main sequence (SFMS), althoughsome galaxies associated with DLAs/sub-DLAs lie below the SFMS, suggesting longer-than-typical gas-depletion timescales. Additionally, we find that the absorption and emission metallicities correlate with 𝑀∗ and sSFR, implying metal-poor absorbers arise ingalaxies with low past star formation and faster current gas consumption rates.
Abstract
Accretion onto young, low-mass stars, known as T Tauri stars (TTS), is the primary source of ultraviolet (UV) photons that drive several physical processes in the inner regions of their surrounding protoplanetary disks. Significant changes in the accretion rate occur on timescales of minutes to years, but the driving forces behind this variability and its effect on the disk are poorly understood. To help characterize these changing UV fields, I will present a large Hubble Space Telescope (HST) UV variability study of TTS, consisting of 31 UV spectra of 5 systems. I will discuss typical changes observed within this dataset and highlight several unique epochs. I will also present results from a simultaneous short-cadence Transiting Exoplanet Survey Satellite (TESS) monitoring campaign of TTS in the Taurus star-forming region. Finally, I will present simulations that make predictions about TTS light curve morphology for various magnetic field configurations and stellar parameters. The lessons learned from these analyses will be applied to the HST Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES), which has devoted 500 orbits to studying accretion onto TTS.
Abstract
One of the key open questions in galaxy evolution is how efficiently galaxies form stars as a function of cosmic time. In order to solve this problem, it is crucial to reconstruct the star formation rate density (SFRD) to the highest possible redshifts. However, the available information at z>3 is limited and biased towards UV-luminous galaxies. One approach is to search for star-forming galaxies (SFGs) at z>3 missed by optical/NIR surveys because of dust obscuration.
In this talk, I will illustrate the potentialities of a radio selection. In particular, I will present the largest homogeneous sample, so far, of Radio-Selected NIR-Dark galaxies, that we have collected in the COSMOS field pairing the radio data from the VLA-COSMOS 3GHz Large Project to a lack of counterpart in the COSMOS2020 photometric catalogue.
I will show the properties of these galaxies, with a particular focus on what we can learn from sub-mm spectra that we collected as part of a dedicated ALMA follow-up campaign. Part of our sample has been/will be observed as part of the COSMOS-Web survey: I will also show how JWST is effectively pulling some of these sources out of darkness and helping us understand their elusive nature.
Finally, I will discuss the likely evolutionary path of these systems that can give a substantial contribution to the cosmic SFRD.
The mere existence of such heavily obscured galaxies in the first two billion years after the Big Bang opens new avenues to investigate the early phases of galaxy formation and evolution, and to understand the links between these systems and the massive galaxies which ceased their star formation at later cosmic times.
Abstract
After a cursory glimpse on the historical foundations of microlithography, this talk will provide you with a solid notion of what can be achieved in nano-lithography today and what the present technical limitations are and what may end up being practical or fundamental boundaries of will be possible in the future. Carl Zeiss SMT has been working on lithography optics for more than 50 years and has lived through many of the technological milestones from the early beginnings of integrated circuits to present-day extreme integration using EUV and allowing qualitatively new applications of micro- or rather nano-electronics. While the technologies involved are more than can be covered in a single seminar, you will get an overview of a wide range of technical aspects that have to be addressed in order to succeed and how we are doing in addressing them. A status update on the latest HiNA EUV optics will be included.
Abstract
A satisfying theory for star or planet formation should not consider these processes in isolation. Leveraging advances in computations and large observational surveys, we are well-positioned to test detailed theoretical models of stellar system formation across diverse galactic environments. We are beginning to couple our understanding of the earliest phases of star formation with the onset of planetary system formation, considering the growth of planets embedded in their natal disks. In this talk, I will review joint constraints on planet formation and star formation. I will highlight how broad demographic trends inform our understanding of the importance of different physical mechanisms. Finally, I will illustrate the outsize impact of small dust grains on the detectability and early evolution of young planets.
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The Thirty Meter Telescope (TMT) is an advanced telescope equipped with a 30-meter segmented primary mirror, designed to be an exceptional tool for exploring the wonders of the universe in the northern hemisphere. With its impressive primary mirror, the TMT surpasses the capabilities of even the JWST(x4) and Hubble telescopes (x12), delivering remarkably clear images. When operational, the TMT will unlock new frontiers in astronomy and astrophysics, enabling us to delve into the intricacies of star and planet formation, unravel the mysteries of galaxy history, and deepen our understanding of the structure of the universe.
In this presentation, we will explore the future prospects of TMT development, focusing on the engineering approach that will ensure its successful performance, functionality, and ease of maintenance. Our aim is to create a system that is on performance, feasible to produce, and straightforward to maintain, while minimizing potential risks.
We will also discuss the ongoing evolution of our engineering approach, continuously improving our methods to maximize efficiency and simplicity.
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I will discuss ways that we can support LGBT people in academic science. LGBT drop out of science careers at greater rates than non-LGBT and experience higher rates of dissatisfaction. I will discuss the national support organisation QueersInScience, of which I am among the founding board members, for LGBT researchers. The group organizes events to highlight LGBT researchers, provides a networking support, and has recently begun LGBT awareness training that is tailored for life in academia.
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We will inform you about funding opportunities for individual researchers within the European Research Framework Programme Horizon Europe, particularly about the Marie Sklodowska Curie Postdoctoral Fellowships and the ERC Starting and Consolidator Grants. PhD students are also very welcome to join!
Abstract
The stellar mass – halo mass relationship is a fundamental scaling relationship connecting galaxies from dwarfs to giants to their dark matter halos. This relationship is currently key to our understanding of the complex interplay between the many modes of feedback (e.g., stellar winds, supernovae, AGN) and star formation in galaxies. However, recently a population of large half-light radius, low surface brightness ultra-diffuse galaxies (UDGs) have questioned our understanding of galaxy formation in the dwarf galaxy regime. UDGs have been found to reside in dark matter halos of widely varying mass. While many likely reside in “normal” dark matter halos for their stellar mass, some may exhibit an extreme lack of dark matter while yet others are extremely dark matter rich. In this talk, I give an overview of the current observational evidence for UDGs residing in massive dark matter halos. I place particular emphasis on my own Keck observations which have provided support for UDGs’ unexpected stellar mass – halo mass positioning and that has revealed the internal structure of their halo (i.e., core vs cusp nature). I discuss how these observations currently inform proposed formation scenarios for UDGs and show an outstanding tension of my observations with simulations of galaxy formation. I conclude with a brief discussion of the important future goals of the field.
Abstract
Direct imaging observations keep on getting better and better and we are now able to detect faint substructures in young debris disks. In a recent paper we reported the detection of a faint arc in the debris disk around the solar-type star HD 129590. This arc is detected in SPHERE total intensity observations but is not recovered in simultaneous polarimetric data. We propose an explanation for this apparent discrepancy, combining the effects of dust properties and dust dynamics. In this talk I will describe the main results of our study as well as the implications it has for our understanding of this rather unique system.
Abstract
The basic principles of X-ray image formation in medical imaging have remained essentially unchanged since the discovery of X-rays by Roentgen over one hundred years ago. The conventional approach relies on X-ray attenuation as the sole source of contrast and uses only ray optics to describe and interpret image formation. This approach ignores another potentially more useful source of contrast, the wave-optic interaction of X-rays with matter. Similar to light microscopy, advanced imaging concepts such as phase-contrast and/or dark-eld scattering imaging can provide tremendous improvements in image quality and sensitivity.
In particular, I will present our recent results from the world's rst application of darkeld radiography on patients, for which we developed, built and installed a rst darkeld chest X-ray system at the TUM university hospital Klinikum rechts der Isar. With this system we could demonstrate that darkeld imaging can signicantly improve the diagnosis of lung diseases such as chronic obstructive pulmonary disease (COPD), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and lung cancer. These ndings are also important from a societal perspective, as respiratory diseases are a major cause of chronic illness and mortality worldwide. While modern medical imaging techniques now provide detailed diagnostic information, there is still a lack of a low-dose, rapid and cost-effective option for early detection and/or follow-up.
Abstract
Open discussion chaired by Nico Hamaus and Nico Schuster
Abstract
Galactic Globular Clusters were for decades considered as the archetype of simple stellar populations and, as such, they were widely used as testing benches for the modelling of stellar evolution and population synthesis tools.
The past twenty years have, however, brought a veritable revolution in our understanding of these objects: we now know that they host multiple stellar populations, with varying characteristics. In spite of considerable effort on the matter in the past two decades, a coherent comprehension of the processes that lead to the formation of these objects is still elusive, with proposed scenarios being challenged by observational evidence. In this talk, I will review the current understanding of phenomenon, focusing in particular on the multifaceted evidence arising from the study of the composition of the multiple stellar populations. I will also discuss on some of the key open issue in this context and explore how the upcoming large spectroscopic surveys (e.g. 4MOST, WEAVE, SDSSV) might impact this topic.
Video
Abstract
Despite the physical limitations of observing faraway worlds, the study of exoplanets has flourished in recent years. Yet, our insight into exoplanet atmospheres has lagged in the exoplanet boom.
Confidently resolved, minute changes in the observed spectral light allow us to trace exoplanet winds both globally and more recently with next-generation facilities in a time-resolved manner as the planet rotates. From this new 3D approach to exoplanetary studies, we can not only paint a picture of the atmospheric dynamics of these worlds but also gather insights into their formation, possibilities for moons, and more. Yet, any of these results rely heavily on our understanding of the instrument in use. I will give a quick overview of the use of ESPRESSO to study exoplanet atmospheres, its advantages, and current challenges.
Abstract
Thanks in large part to Gaia observations of the Milky Way and rapid advances in data science, it has very recently become possible to map out: 1) the three-dimensional internal structure and galactic arrangement of star-forming regions and 2) the positions and motions of young stars forming in those regions—also in 3D. These advances are painting a NEW picture of NEW (freshly-formed!) parts of the Milky Way. The 3D, moving picture we can re-create from the data is giving hints as to the origins of oscillations in the Galaxy's arms (e.g. The Radcliffe Wave) as well as to the role of feedback (e.g. in the Local Bubble) from supernovae in driving the formation of dense gas, and ultimately stars. The talk will focus primarily on science, while also including demonstrations of how data science and visualization tools, including glue, WorldWide Telescope and OpenSpace, have enabled these discoveries.
Abstract
Paper: https://arxiv.org/abs/2302.04711
Abstract
The detection of several X-ray-quiescent black-hole (BH) binaries via single-lined spectroscopy has been recently reported for the first time. Here we present the implications on natal kick during BH formation for the most massive source of this population: VFTS 243. With a BH mass of 9.1 ± 1.0 Msun, an eccentricity of e = 0.017 ± 0.012, and no apparent X-ray-emitting accretion disk, the BH of VFTS 243 is a strong candidate for the complete collapse scenario. This scenario suggests stellar collapse without an explosion and therefore mass ejecta exclusively lost via neutrino emission. We explore the natal kicks of VFTS 243 and find that the current orbital configuration is consistent with the complete collapse scenario. I present the preliminary results of this exploration and the implications to neutrino natal kicks and asymmetries during BH formation.
Abstract
The formation of stars at low metallicities is a central problem in galaxy formation and evolution, i.e., to understand the properties of the high redshift universe. However, studies of the detailed star formation process in low metallicity environments have been limited due to large distances and the corresponding difficulty in characterizing low-mass sources. Here I will present a multi-wavelength campaign that employs the synergy of ALMA and JWST to characterize star formation processes of Sh2-284, one of the lowest metallicity proto clusters in the Galaxy.
Abstract
The astrochemical space is complex and diverse. Even though, our understanding about the astrochemical inventories is continuously increasing, we just know very little about the molecules' interactions and their reaction networks. In this talk, I will present how graph-based Network Analysis unveils how many ten thousand different astrochemical species in interstellar ice analogs are connected to each other. This has implications for probing system's properties, e.g. emergence or collective, synergistic features.
Abstract
Catalytic particles are spatially organized in a number of biological systems across different length scales, from enzyme complexes to metabolically coupled cells. Despite operating on different scales, these systems all feature localized reactions involving partially hindered diffusive transport, which is determined by the collective arrangement of the catalysts. We explore how different arrangements affect the interplay between the reaction and transport dynamics, which ultimately determines the flux through the reaction pathway. Two fundamental trade-offs arise, the first between efficient inter-catalyst transport and the depletion of
substrate, and the second between steric confinement of intermediate products and the accessibility of catalysts to substrate. We find that the question of optimal catalyst arrangements generalizes the well-known Thomson problem of electrostatics [1]. Furthermore, we map the problem of optimally arranging enzymes to an economic investment problem, which helps to formulate and understand a possible design principle for synthetic biomolecular systems [2].
[1] F. Hinzpeter, F. Tostevin, A. Buchner, and U. Gerland (2022), Trade-offs and design principles in the spatial organization of catalytic particles, Nature Phys. 18, 203-211.
[2] G. Giunta, F. Tostevin, S. Tanase-Nicola, and U. Gerland (2022), Optimal spatial allocation of enzymes as an investment problem, Commun. Phys. 5, 319.
Abstract
The Large scale Structure of the Universe is organised in a Cosmic Web made of voids, sheets, nodes, and filaments that are well traced by the distribution of galaxies. Numerical simulations suggest that the filamentary structure between clusters of galaxies at the nodes of the Cosmic Web contains about 40% of the total baryons in the form of a hidden ionised warm/hot component.
I will present how we can combine the use of surveys in the optical, in the millimetre (via the Sunyaev-Zel'dovich and CMB-lensing signals measured by Planck), and in the X-rays to study the filamentary structure of the Cosmic Web and to unveil its content. Combining these observables, we have detected the Cosmic Web filaments and we have tackled the problems of measuring their warm/hot baryon content and of characterising its properties.
Video
May 2023
Abstract
Until now, direct observations of the intracluster medium (ICM) have been limited only to mature clusters in the latter three-quarters of the history of the Universe, and we have been lacking a direct view of the hot, thermalised cluster atmosphere beyond z~2, the epoch when the first massive clusters formed. Probing the thermal evolution of cosmic structures through z~2 — the epoch when intracluster gas starts to assemble and virialise, and cosmic star formation and the activity of active galactic nuclei (AGN) manifest a concurrent peak — is however crucial for exploring the link between galaxy clusters and their over-dense progenitors, as well as finding the observational fingerprint of feedback effects that regulate the later coevolution of the galaxy and intracluster/circumgalactic medium ecosystems.
In my talk, I will present our recent detection of the thermal Sunyaev-Zeldovich (SZ) effect in the direction of the protocluster complex surrounding the famous Spiderweb Galaxy (z~2.16), made possible only thanks to the superior capabilities of the Atacama Large Millimeter/Submillimeter Array (ALMA). Such identification of a nascent intracluster halo represents the unambiguous proof that we are witnessing the transition through which a sparse overdensity of galaxies turns into a massive galaxy cluster, providing a statistically meaningful confirmation of long-standing predictions from cosmological simulations, and cluster and galaxy evolution.
Abstract
In this talk I will present preliminary results of dust properties constraints around six transition disks (CQTau, DMTau, LkCa15, RXJ1615, SR24S, and UXTau), where ALMA and VLA continuum emission visibilities have been analyzed.
In the first part of the talk I will focus on the visibility modeling used to infer the brightness radial profiles of the multi-wavelength emission, and then I will present how we use this information to model the radially-resolved SED, where dust trapping signatures are expected if the cavity has been created by a gap or a dead-zone.
Abstract
Supermassive black holes of 10^10 solar masses already existed at z~6-7, when the Universe was less than 1 Gyr old. To reach this mass in such a short time they should have started as seed intermediate-mass black holes (IMBHs) of 100-10^6 solar masses at z > 8.
I will show that a population of actively accreting IMBHs exists in local dwarf galaxies and that they can be detected out to z~3 with the use of deep multiwavelength surveys. Whether these are the relics of those early seed black holes that did not grow into supermassive is still a matter of debate, since processes such as dwarf galaxy mergers and black hole feedback can have a very strong impact on black hole growth. The next generation of observational facilities could open a new window by detecting seed IMBHs at birth.
Video
Abstract
This talk will be a tour de force through the history of nature – from the beginning of the Universe until today. It will be a tour de force along one line, namely the major property of all natural systems, they become unstable and drive irreversible changes when they reach energetical limits. They organize themselves by critical processes, exceeding stability criteria.
The talk will deal with primordial density fluctuations and external gravitational and thermodynamical influences on boundary and initial conditions, the role of different surfaces, gradients, turbulence and other complex sources of free energy which drive changes in structures on all scales. It will emphasize the importance and limitations of the ideal mathematical description of complexity and illuminate the very special role of boundary conditions by serving with the facts. The facts are the central information about what has happened and what is real and they show how important instabilities are, because they create the structures in the Universe from galaxies to stars and planets, from planets to life and mind, from mind to science and responsibility.
Finally, we will end up with the suggestion to found a new faculty on universities: Faculty for tipping points and transformation studies in nature and society. Interdisciplinarity is more important than ever and if we don’t do it at the universities, where else?
Abstract
In my first postdoc year in the US, I published a paper in Science on the discovery of water plumes on Jupiter’s moon Europa. The paper and the results had large impact in the field and in the community and even possibly affected the decisionfor NASA’s Europa Clipper mission. This certainly helped my career but it also was a burden at times and defined the perception of myself by the community more than I wanted. I will tell the story about the discovery and my role in it.
Abstract
Models of planetary core growth by either planetesimal or pebble accretion are traditionally disconnected from the models of dust evolution and formation of the first gravitationally bound planetesimals. State-of-the-art models typically start with massive planetary cores already present. We aim to study the formation and growth of planetary cores in a pressure bump, motivated by the annular structures observed in protoplanetary disks, starting with submicron-sized dust grains. We connect the models of dust coagulation and drift, planetesimal formation in the streaming instability, gravitational interactions between planetesimals, pebble accretion, planet migration, gas accretion and gap opening into one uniform framework. We find that massive cores in a pressure bump can remain at wide orbits and grow by gas accretion towards gas giants on a timescale of less than 0.5 Myr. Subsequently, one or more planetary gaps are opened in the disk and dust is trapped at the outer pressure bump. Similar to the initial pressure bump, a new generation of planetesimals is formed at the new pressure bump, which again grow by pebble accretion and then by gas accretion. The model demonstrates that sequential planet formation is possible. By adjusting the parameters, this model can potentially produce a wide range of planetary system architectures, including that of the outer Solar System.
Abstract
I will discuss the transmission electron microscope (TEM) and the scanning tunneling micros- cope (STM). I will continue with a short history of in situ microscopy where one part is that we at Chalmers developed a system where we inserted an STM into the TEM holder to have the two techniques simultaneously. After this, I will show how the combination of the two important inventions provides access to the 2- and 3-dimensional atomic structure of materials. While STM provides high spatial resolution information about the surface, the TEM also gives access to both surface and sub-surface structure and properties. As an example of the importance of precise atom positions for the material properties, I demonstrate the extreme situation where a high electric eld breaks the bonds and melts gold surfaces at room temperature.
Abstract
The Intracluster Medium (ICM) of galaxy cluster is a hot, X-ray emitting gas in the plasma state. Turbulence driven by AGNs jets and cluster mergers is an attractive heating source to counteract its intense radiative cooling. In this discussion, I will present a mechanism in which large scale turbulence can directly heat the plasma at small scales, bypassing the turbulent cascade via a process called magnetic pumping. I will describe its theoretical basis, provide a plot of our numerical simulations and discuss the implications for the heating of the ICM.
Abstract
I will report a CO(3-2) detection of 23 molecular clouds in the extended ultraviolet (XUV) disk of the spiral galaxy M83 with ALMA. The observed 1kpc2 region is at about 1.24 R25 from the disk center, where CO(2-1) was previously not detected. The detection and non-detection, as well as the level of star formation (SF) activity in the region, can be explained consistently if the clouds have the mass distribution common among Galactic clouds, such as Orion A -- with star-forming dense clumps embedded in thick layers of bulk molecular gas, but in a low-metallicity regime where their outer layers are CO-deficient and CO-dark. The most massive clouds appear similar to Orion A in SF activity as well as in gas mass. The common cloud mass structure also justifies the use of high-J CO transitions to trace the total gas mass of clouds, or galaxies, even in high-z universe. This study is the first demonstration that CO(3-2) is an efficient tracer of molecular clouds even in low-metallicity environments. In addition, if time allows, I will also briefly show a new high-fidelity CO(1-0) imaging of the full optical disk of M83 with ALMA 12m+7m+TP (435-point mosaic) at 40pc resolution with a mass sensitivity of 10^4Msun.
Abstract
The generation of single isolated attosecond pulses in the extreme ultraviolet (XUV) together with fully synchronized few-cycle infrared (IR) laser pulses allowed to trace electronic processes on the attosecond timescale. A pump/probe technique, "Attosecond streaking'" has been used to investigate electron dynamics from gases, liquids, solids, layered systems and molecules on surfaces with unprecedented resolution. These measurements lead to a stepwise increase of the understanding of different physical effects contributing to the timing of photoemission. Evaluation of streaking traces needs quite an amount of computation and time. Deep learning has been applied to reconstruct streaking traces and made possible to compare them online to reconstructed traces.
Abstract
The Canadian Cosmological Hydrogen Intensity Mapping Experiment (CHIME) is an ambitious new approach for rapid surveying of the radio sky. The first results from its time domain back end include the leading discovery machine for fast radio bursts, resulting in large catalogs to study their nature and open up coherent applications for precision cosmography. I highlight some results from synergy with follow-up collaborations, including the connection to globular clusters, periodicity, and polarization. Other survey modes include 21cm mapping in emission and absorption, polarimetry, pulsar studies, and direct VLBI. This opens the path for a next generation of more ambitious all sky surveys, of which I will describe the ongoing BURSTT initiative.
Video
Abstract
During the COVID-19 pandemic, mobile phone data sets have been used all over the world to measure the effectiveness of mobility restrictions and to inform epidemiological models of disease dynamics. However, there are several issues with mobile phone datasets that have not been thoroughly investigated, and which can cause serious impacts in the conclusions drawn from the studies using these data, and their implementation or impact in public policy, for example. Here we discuss three of these issues: Modifiable area units (MEAP) and the politics of administrative boundaries, common evaluation techniques of trip/mobility algorithms, and the ethics/responsibility of data sharing. Some of these issues have straightforward methodologies (even if not solutions per se, such as the MEAP), others have straightforward solutions, but haven’t been discussed yet (trip evaluations), and others are downright difficult to reach a common ground, such as the sharing of private, sensitive, commercial data. In this work, we discuss a few solutions to each of these issues, and open the door for a more open scientific discussion.
Abstract
Andromeda galaxy (M31) is the closest spiral galaxy to our own Milky Way. Due to its proximity, it is a galaxy that has been observed in detail, including chemistry, kinematics and stellar populations from the centralregions to its halo, over a field of view of nearly 100 degrees squares. The observed number density map of its extended halo (PAndAS) present some archetypal signatures of accretion events. Apart from this, there are also data from its stellar disc and innerhalo fields that are indicative of a major merger event in its recent past.
In this Informal Discussion, I will present the main observational data we have for M31, and try to highlight especially those that point to the direction of a major merger (mass ratio ~1:4) event that created thedisc of M31, as well as the spatial distribution of the observed substructures in its inner halo. I will present the main features of an N-body, hydrodynamical simulated model of a major merger paradigm for the formation of M31 and briefly talk about my currentwork on comparing the predictions of this model with data from M31's disc, inner halo and its faint substructures.
Abstract
The Jupiter Icy Moons Explorer (Juice) was successfully launched on 14 April 2023 from Guiana Space Centre by the European Space Agency (ESA). The main objectives are the characterization of Jupiter’s ocean-bearing icy moons – Ganymede, Europa and Callisto – as planetary objects and possible habitats, the exploration of Jupiter’s complex environment, and overall the study of the Jupiter system as an archetype for gas giants. The spacecraft with its 11 science instruments will arrive at Jupiter in July 2031 and finally go into orbit around Ganymede in 2034. I will give an overview on the instrumentation and mission design, and explain in more detail the magnetic sounding of Ganymede's subsurface ocean as an example key investigation.
Abstract
Doped two-dimensional antiferromagnetic Mott insulators exhibit many exotic phenomena, such as pseudogap or strange metal behavior. Establishing a microscopic understanding of the intricate interplay between hole motion and magnetic correlations of these strongly-correlated states has challenged researchers for decades and still poses many open questions. We de- veloped a bilayer quantum gas microscope to study two-dimensional Fermi-Hubbard systems prototype examples of antiferromagnetic Mott insulators with spin and charge (density) resolution at the single-particle level. Our setup enabled a direct real-space characterization of correlations between spins and charges up to higher order at temperatures around the superexchange energy. At weak dopings, we reveal the dressing of dopants by a local modi- cation of magnetic correlations the so-called ``magnetic polaron''. Upon increasing doping, we observed the crossover from a polaronic metal to a Fermi liquid at dopings around 30%. Future technological upgrades of our quantum simulator promise to shed new light on lower temperature phenomena, such as hole pairing or stripe phases.
Abstract
State-of-the-art 3D simulations lend support to the neutrino-driven explosion mechanism for explaining the majority of core-collapse supernovae. Using this paradigm it has been shown that 3D explosion models can explain the multi-band light curves and spectra of low-energy Type IIP supernovae such as Crab; they can also reproduce basic elements of the 3D morphology and the gamma-ray lines of the Cassiopeia A remnant; and they provide new hints on the binary nature of the SN 1987A progenitor and the most likely location of the compact remnant in its ejecta nebula. The talk will summarize this progress of 3D supernova modelling and will outline the open questions and routes of ongoing research.
Video
Abstract
Paper: https://iopscience.iop.org/article/10.3847/1538-4357/acbf34
Abstract
A significant fraction of all stars forms in binary or higher-order systems. Stellar multiplicity is even more ubiquitous for massive stars: almost all O-stars have at least one companion, and many of them transfer mass to a companion over their lifetimes. Those interactions shape the feedback from massive stars. Most stars also form within clustered environments, where binary systems are formed, modified, or destroyed through gravitational dynamics. It is therefore crucial to account for the interplay between binaries and the larger-scale cluster environment to paint a complete picture of star cluster formation.
In this informal discussion, I will present key results from simulations of star cluster formation with hydrodynamics, stellar dynamics and feedback, and sub-grid star and binary formation. I will also discuss ongoing work on the implementation of feedback from massive interacting binaries in those simulations. I will conclude by highlighting what kind of observational results would be helpful to the design of our feedback model.
Abstract
I will present results from 18 intermediate redshift clusters with spectra of about 3600 cluster members. This enabled us to use the location of star-forming (SF) galaxies, recently quenched galaxies (RQGs) and active galactic nuclei (AGN) in the projected velocity vs. position phase-space (phase-space diagram) to identify objects in the inner regions of the clusters. We found the metallicities of SF cluster galaxies with R<R200 to be enhanced with respect to the mass-metallicity relation of coeval field SF galaxies. Interestingly, this metallicity enhancement is limited to lower-mass satellites of the 9 clusters with a passive brightest cluster galaxy (BCG). A higher fraction of higher mass SF galaxies at R<R500 in the 9 clusters with active BCGs compared to the 9 clusters with passive BCGs is a signal for Galactic Conformity. On the other hand, much higher fractions of AGN and especially RQGs at R<R500 are found in clusters with passive BCGs in comparison to clusters with active BCGs. We conclude that strangulation is initiated in clusters with passive BCGs when SF satellite galaxies pass R200. Galaxies with higher masses which survived to be SF when traveling to R<R500 of clusters with passive BCGs suffer a rapid quenching of star formation, likely due to AGN triggered by the increasing ram pressure stripping toward the cluster center, which can compress the gas and fuel AGN; these AGN can rapidly quench and maintain quenched satellite galaxies.
The observed galactic conformity tells us that there is still an additional unknown "hidden common variable" that is affecting the quenching of both satellites and centrals. Since the current quenching mechanisms are too strong in the simulations (e.g., Magneticum Pathfinder, IllustrisTNG) compared to observations, new theoretical simulations with more realistic quenching mechanisms in clusters are needed in order to explore the reasons for the observed conformity.
Abstract
T Tauri stars are low-mass pre-main sequence stars that are intrinsically variable. Due to the intense magnetic fields they possess, they develop dark spots on their surface that, because of rotation, introduce a periodic variation of brightness. In addition, the presence of surrounding discs could generate flux variations by variable extinction or accretion. Both can lead to a brightness decrease or increase, respectively. Here, we have compiled a catalogue of light curves for 379 T Tauri stars in the Lagoon Nebula (M8) region, using VVVX survey data in the Ks-band. All these stars were already classified as pre-MS stars based on other indicators. The data presented here are spread over a period of about eight years, which gives us a unique follow-up time for these sources at this wavelength. The light curves were classified according to their degree of periodicity and asymmetry, to constrain the physical processes responsible for their variation. Periods were compared with the ones found in literature, on a much shorter baseline. This allowed us to prove that for 126 stars, the magnetically active regions remain stable for several years. Besides, our near-IR data were compared with the optical Kepler/K2 light curves, when available, giving us a better understanding of the mechanisms responsible for the brightness variations observed and how they manifest at different bands. We found that the periodicity in both bands is in fairly good agreement, but the asymmetry will depend on the amplitude of the bursts or dips events and the observation cadence.
April 2023
Abstract
The newly launched James Webb Space Telescope (JWST) has expanded our cosmic horizon to the first few hundred million years after the Big Bang, enabling us to observe the build up of the first galaxies. These first galaxies fundamentally altered their surroundings by 're'-ionizing intergalactic hydrogen. I will describe how this reionization process is still poorly understood, but how identifying which population of galaxies dominated the process is key to constraining poorly understood astrophysics of galaxy formation (e.g. massive star formation and feedback processes). Excitingly, an excess of luminous galaxy candidates just 500 million years after the Big Bang has been discovered in early JWST data, which exceeds theoretical predictions. I will discuss how the new JWST observations test theoretical models and possible solutions. I will present efforts to constrain the timeline of reionization, which favour a late and rapid end to reionization. I will discuss how JWST observations of Lyman alpha emission at z>8 challenge these results and discuss the implications for our understanding of early star formation.
Video
Abstract
Photonic circuits are of growing importance in astronomical instruments. Seeing limited, bulk optic spectrographs scale in mass and cost with the size of the telescope diameter as D^2 to D^3. This fundamental limitation can be overcome with photonic waveguides, thanks to the tremendous progress in adaptive optics over the last decade. A photonic spectrograph is independent of the telescope size. This fundamental advantage motivated our development of a photonic dispersive chip, working in the astronomical J-band (1.1-1.4 μm) with a spectral resolution of R~10,000 based on an arrayed waveguide grating design. The chip features three input channels, fed by single mode fibers. The output region is diced such that the spectrum can be re-imaged on a detector. The design parameters were a trade-off between spatial resolution and availability of adaptive optics correction and science requirements. The SiO2 chip manufacturing was contracted to an industrial partner. The performance verification has been done on a testbed developed at ESO. The development and characterization of the prototype chip will help to understand if this technology can be employed in future instruments.
Abstract
Line-Intensity Mapping (LIM) is an observational technique that uses integrated emission lines from gas clouds to extract information about cosmology and extragalactic astrophysics. Unlike galaxy surveys, this technique samples even the sources which are not so bright and can reach very high redshifts to probe very large cosmological volumes. In order to extract valuable information from upcoming LIM surveys, we will need robust models to infer astrophysical/cosmological parameters from observed luminosities. In this talk, I will give an overview of the field, and present the framework I have been developing to contribute to LIM modeling. I generate LIM light cones fully based on cosmological hydrodynamic galaxy formation simulations, combined with thermal/radiative/chemical equilibrium photodissociation region (PDR) models to calculate the spectral line luminosities from every gas particle in the snapshots. In addition, I will show an application of this framework using the SIMBA simulations to generate CO and [CII] mock light cones.
Video
Abstract
Gas is a fundamental component of galaxies and its chemical composition is key for the chemical evolution of galaxies and the cosmic chemical evolution. The metal content of the neutral gas inside and around galaxies (Interstellar and Circumgalactic Medium) can be probed in great detail with absorption-line spectroscopy of stars in the Local Group or distant quasars and gamma-ray bursts (GRBs). However, the presence of dust dramatically alters the observed metal abundances, because of the depletion of metals into dust grains. I developed a technique to derive metallicities, dust depletions, and additional nucleosynthesis signatures in the gas from the observed relative abundances of metals, based on the fact that different metals have different tendencies of depleting into dust, and different metals have different nucleosynthetic origins. This is key for a deeper understanding of the chemical content of the neutral ISM/CGM in galaxies and allows us to start addressing new questions. What is the metallicity of the neutral ISM in our Milky Way? Are metals distributed uniformly in galaxies? Can we observationally study the chemical evolution of distant galaxies? How does the metallicity in the neutral gas evolve with cosmic time? What is the role of massive stars in the chemical enrichment of the early universe, and how can we observe it? In this talk I will review exciting results addressing these questions.
Video
Abstract
Nuclear star clusters (NSCs) are dense, massive star clusters found in the centres of at least 70% of all galaxies. NSCs are known to co-exist with central black holes (BHs), our own Milky Way being the most prominent example, and are known to follow the same scaling relations with host galaxy properties, suggesting a connected evolution. However, unlike BHs, NSCs still contain records of their formation and evolution imprinted in their stellar populations. Generally, two main scenarios are discussed for NSC formation that are ultimately linked to the evolution of galaxies and their star cluster systems: NSCs might form in-situ from gas at the galactic centre, a process that is linked to galactic star formation and dependent on the availability of gas. Alternatively, NSCs might form from the (dissipationless) accretion of globular clusters that spiral inwards due to dynamical friction. Most likely, a mixture of both pathways is realized in nature.
In this informal discussion, I will discuss how MUSE data can be used to disentangle the dominant NSC formation channel in individual galaxies and will present a clear dependence of the dominant NSC formation channel from globular cluster-accretion being the dominant channel in dwarf galaxies to in-situ formation forming massive NSCs in massive galaxies.
Abstract
We have now assembled a great programme for the RU-D Day that includes a set of morning science talks and a brain-storming session in the afternoon about the future of ORIGINS.
Hence, please join us on Wednesday, April 19, for the ORIGINS RU-D Day in the Eridanus auditorium at ESO Garching.
Simona, Eleonora, Eric
on behalf of RU-D
Abstract
Quasars are widely used in astrophysics to probe various environments, ranging from large-scale studies of clustering and the intergalactic medium to galactic-scale studies of the interstellar and circumgalactic media. Moreover, quasars are intriguing objects on their own and many aspects of quasar evolution and the multitude of observational phenomena are still not fully understood. One main limitation to quasar studies in general is the pre-selection for spectroscopic observations. The largest spectroscopic quasar samples to date have been selected based primarily on optical colors with in-homogeneous inclusion of multi-wavelength data to increase purity. Such identifications may lead to potential biases and can have severe consequences for foreground absorption studies. In this talk, I will highlight our efforts to obtain the first color-independent quasar sample by selecting candidate quasars purely based on astrometry from Gaia. This method allows us to select a sample of optically bright quasars with no further assumptions on the spectral shape. The talk will focus on the implications for studies of foreground absorption systems in particular the absorption systems caused by cold and molecular species (CI and H2).
Abstract
Globular clusters (GCs) have long held promise to provide powerful insights into how galaxies form and evolve. Unfortunately, the challenges of dating of GCs in distant galaxies has prevented us to unlock their potential to trace galaxy assembly. Here I show how we have overcome the longstanding problem in the determination of ages of extragalactic GCs using models with flexible properties of horizontal branch stars. Then I will how the improved dating method has allowed us to reconstruct the properties of the progenitor of the most recent accretion event in Andromeda. These results have opened the door for galactic archeology studies in the local volume.
Abstract
With a new generation of large etendue monitoring survey telescopes, there is a growing need for a number of real-time processing tasks that include: data processing for alert generation, annotation and classification, and reaction to those alerts deemed interesting optimizing the use of available follow-up facilities. In this talk, I will introduce an alert classification and reaction system called ALeRCE: Automatic Learning for the Rapid Classification of Events. ALeRCE has been selected as one of the official brokers for the Vera Rubin Observatory, and it is currently processing the Zwicky Transient Facility (ZTF) alert stream, providing machine learning classifications for variable stars, active galactic nuclei, SNe, and asteroids.
Then, I will give a short hands-on tutorial on how to use some of the ALeRCE tools publicly available for the astronomical community. So if you want to be notified when your favourite object(s) changes(), or discovery new candidates to any of the classes that we work with, come along and bring your laptop.
Abstract
The Central Molecular Zone (CMZ) is a ring-like accumulation of molecular gas in the innermost few hundred parsecs of the Milky Way, generated by the inward transport of matter driven by the Galactic bar. The CMZ is the most extreme star-forming environment in the Galaxy. The unique combination of large-scale dynamics and extreme interstellar medium conditions, characterised by high densities, temperatures, pressures, turbulent motions, and strong magnetic fields, make the CMZ an ideal region for testing current star and planet formation theories. In this talk, I will review the recent observational and theoretical advances in the field, and combine these to draw a comprehensive, multi-scale and multi-physics picture of the cycle of matter and energy in the context of star (and planet) formation in the closest galactic nucleus.
March 2023
Abstract
The speaker Tom Sparks (MPI for Comparative Public Law and International Law, Heidelberg) approaches the study of climate change as a lawyer, and his
disciplinary training does not prepare him to engage with the climate crisis as a physical phenomenon. Yet climate law and climate litigation, often touted as one of the most promising routes to effective action on climate change, depend for their success on a sophisticated appreciation of climate science. Climate negotiations, meanwhile, are - or should be - the process of capturing in a negotiated, legal form the outcomes of processes which combine scientific knowledge with sociological, economic, moral, and real-political considerations.
Few branches of knowledge are not implicated in solving complex, all-society problems, of which human-induced climate change is the example par excellence. The specialisation of academia within ever-narrower sub-disciplines has been of crucial importance in advancing the progress of science. But given the progress of specialisation both within and especially between disciplines, how can different fields be brought into conversation for the purpose of tackling complex, multi-scalar problems like climate change? In this talk the speaker wants to think through some of these challenges with the audience, using two examples: first, from his own work, the challenges associated with translating climate science into a form useable by international courts; and secondly, from the perspective of the MPG, how we can mobilise our resources to effectively contribute to the processes of international climate negotiations. Tom Sparks coordinates MPG delegation participation at the UN Climate Change Conferences (Conference of the Parties, COP) on a volunteer basis and has participated in recent COPs himself.
Abstract
Fifty years ago, Bekenstein recognized a profound relation between spacetime geometry and quantum information: a black hole carries entropy, in proportion to the surface area of its horizon. This implied that Einstein’s seemingly classical theory of gravity can count its own quantum states, and those of matter.
Today, the entropy-area relation has been vastly generalized, driving a golden age of progress. Gravity has been used to show that the universe behaves like a hologram; that information escapes from a black hole; and that what we perceive as energy density is really a change in the flow of quantum information.
Video
Abstract
Paper: https://arxiv.org/abs/2301.04103
Abstract
MOONS is a 0.8 to 1.8 microns multi-object spectrometer for the Nasmyth focus of UT1 that is being built by a consortium led by the UK-ATC. The instrument is fibre fed, has a multiplex of 1000 and covers a total field of 25 arc minutes in diameter with a high transmission. There are two spectral resolving powers, ~4000 spanning the full wavelength range and a higher resolution mode which gives ~9000 in the I window and ~20,000 in a region in H windows. The instrument itself has two main parts:
The rotating front-end which is at the focal plane and houses the fibre positioners, acquisition system, metrology system for the fibres, etc., and
The cryogenic spectrograph which houses the spectrograph optics, VPH gratings and detectors.
MOONS is now approaching completion and is due to be shipped to Paranal at the end of the year. This talk presents the MOONS instrument, the science that it will allow, and its current status.
Abstract
Luminosity bursts in young FU Orionis-type stars warm up the surrounding disks of gas and dust, thus inflicting changes on their chemical and dust composition. Determining the underlying physical mechanism for the burst from the light curve was proven difficult. Using numerical hydrodynamics simulations I will compare several burst-triggering mechanisms and demonstrate that disk kinematic and morphological features may be used to distinguish between them.
Furthermore, I will report on the effects that such bursts may have on the spatial distribution of dust grain sizes and the corresponding spectral index in the surrounding protoplanetary disk. The burst causes the water snowline to move radially outward, resulting in the drop of the maximum dust size interior to the snowline position. A broad peak in the radial distribution of the spectral index in the millimeter dust emission develops at several astronomical units, which shifts further out as the disk evolves and dust grains regrow to pre-burst values. I demonstrate that, depending on the burst strength and disk conditions, the peak in the dust spectral index can last for up to several thousand years after the burst has ended and can be used to infer past luminosity bursts in otherwise quiescent protostars. The detection of a similar peak in the disk around V883 Ori, an FUOrionis-type star with an unknown eruption date, suggests that such features may be common in the post-outburst objects.
Abstract
The last decade of ALMA has transformed our view of planet-forming environments in all respects. High resolution images have revealed a diverse array of structured belts of millimeter-sized dust and a variety of distinct molecular compositions both within disks and between different disk systems. How does this diversity translate into the initial conditions for the formation of planets and the compositions (gas and solid) that they receive? Are planets likely to receive water and organic material at formation, or at some later phase from a belt of volatile-rich icy comets? I will present an overview of how our picture of the chemical and physical environment of planet formation has shifted in recent years, how this has pushed us to revise models, and how multiwavelength observational campaigns, including upcoming JWST programs, can help us find patterns in the apparent variety of protoplanetary environments.
Video
Abstract
Most studies of galaxy formation suggest that merging supermassive binary black hole systems should be reasonably common in galactic nuclei, but LISA, the observatory with the most robust detection method, remains at least a decade in the future. On the other hand, there are good reasons to expect that many of these binaries accrete gas at a sizable rate. Such a situation motivates searches for them now, using photon telescopes, but there is much uncertainty about what signatures are both reliable and detectable.
In this talk, I will review the various suggestions made hitherto and then present a summary of the light that has been shed on this question by recent numerical general relativistic magnetohydrodynamics simulations, some of them following the evolution of the binary very nearly all the way to merger. These simulations have uncovered entirely new accretion pathways as well as new ways to power photon emission.
Video
Abstract
From erasure and exclusion to intersectionality and justice, the fight to further gender equity in academia is not a new one. And as with all social justice work, it has undergone major changes over time. In this lecture I will discuss the ways in which the framework of gender equity in academia has evolved alongside our understandings of gender and indeed equity. I will also touch on what this work could look like in future. Lastly, I will leave the audience with a homework challenge to further the discussion!
Abstract
MAVIS, the MCAO-Assisted Visible and Imager and Spectrograph, is quite a challenging instrument, considering we need to maintain the phase error below 125nm RMS at any point within the science field of view of 30” diameter. We can’t be sloppy and let error budget terms drift. We have developed a number of improvement in control, calibrations, etc, that will help us to delivered the required image quality. I will concentrate on these "AO tricks".
Abstract
Dust scattering halos have been utilized to study spectral variations during eclipses, physical properties and distribution of dust grains in the interstellar medium (ISM), X-ray extinction and source distance determination using X-ray flux evolution and radial distribution of X-ray rings. We have obtained a Chandra image of dust scattering halo of 4U 1630-47 and used it together with low resolution 12CO images to place a constraint on the distance of the source in Kalemci et al. 2018. While the preferred distance of the analysis was 11.5 kpc, it was not possible to rule out an alternative distance of 4.7 kpc based on the distance to the prominent dust cloud. We recently obtained very high resolution radio images with the Atacama Pathfinder Experiment (APEX) which provided the exact distribution of molecular clouds in the region allowing us a much detailed spatial analysis of dust scattering. In this presentation we will discuss our findings including distance constraints for the source and molecular clouds.
Abstract
What is the relationship between astronomy and colonialism? This question has been discussed extensively within parts of the astronomical community after indigenous demonstrators blocked the construction of the Thirty Meter Telescope on Hawai'i in 2014. In this informal discussion, I will approach the question with the help of material that I found while doing research for a popular science book about black holes. In particular, I will show previously unpublished material from the archive of Karl Schwarzschild that elucidates the surprising link between black hole science and colonialism.
Abstract
The recently reported association between the blazar TXS 0506+056 and high energy neutrinos by the IceCube experiment provided the possibility to perform the first multi-wavelength and multi-messenger analysis. The interpretation of this data set requires detailed spectral predictions, which can only be obtained numerically by solving the multi-species kinetic equations. To this end, we developed the code SOPRANO (Simulator Of Processes in Relativistic AstroNomical Objects). In this talk, I will first report on the development and capabilities of SOPRANO, and then, I will present recent results obtained with SOPRANO in the context of blazars SED.
Abstract
The Fornax galaxy cluster provides an unparalleled opportunity to investigate galaxy formation and evolution in a dense environment. Although the Fornax cluster seems relaxed, various studies have shown that the Fornax cluster still is accreting various sub-groups. Photometric studies of the central massive galaxy NGC 1399 revealed an excess of globular clusters (GCs), suggesting the accretion of GCs from nearby, interacting major galaxies like NGC 1404. Using the spectroscopic data from the Visible Multi-Object Spectrograph at the Very Large Telescope (VLT/VIMOS), we have kinematically characterized the photometrically detected GC candidates in the core of the cluster and produced the most extensive radial velocity catalogue of GCs in Fornax.
To understand the mass assembly of the Fornax cluster, we used this catalogue to perform dynamical mass modelling of NGC 1399 out to 200 kpc. We have investigated the effect of the intra-cluster GCs in mass modelling. Independent of the dark matter halo profiles used in modelling, we find that intra-cluster GCs have mild radial anisotropy, suggesting their accreted nature. In this talk, I will discuss the kinematic sub-structure of the intra-cluster GCs, marking the current Fornax cluster assembly. In addition, I will discuss the impact of the intra-cluster GCs on the cluster mass profile.
Abstract
Neutral atomic hydrogen (HI) is a crucial component of the Milky Way and a protagonist in the cycles of energy and matter that lead to the formation of stars. I will present a study of the filamentary structure identified in the HI emission at 21 cm using the HI4PI and the HI/OH/Recombination-line (THOR) surveys of the Galactic plane. We found that the Milky Way’s disk regions beyond ten kiloparsecs and up to roughly 18 kiloparsecs from the Galactic center display HI filamentary structures predominantly parallel to the Galactic plane. However, we also found that the HI filaments are mostly perpendicular or do not have a preferred orientation with respect to the Galactic plane for regions at lower Galactocentric radii. Using the insight from numerical simulations, we interpret these results as the imprint of supernova feedback in the inner Galaxy. We also studied the carbon monoxide (CO) emission observations from The Milky Way Imaging Scroll Painting (MWISP) survey. We found that the orientations of the filamentary structures traced by CO emission differ from those in the HI emission. We interpret this result as indicating that the molecular structures do not simply inherit these properties from parental atomic clouds. Instead, they are shaped by local physical conditions, such as stellar feedback, magnetic fields, and Galactic spiral shocks.
Video
Abstract
We know by now that many stars live their lives in binary or higher-order multiple systems. Many of those systems are close enough to interact during their lifetimes, leading to a diversity of different pathways for the future evolution. Nevertheless, the outcome of such interaction and the nature of post-interaction systems remains fairly unconstrained.
In the informal discussion, I want to explain how we can use young and massive star clusters to spot a variety of binary interaction products, not only blue stragglers that are most likely the most prominent members of their class. I will use one particular example cluster, NGC 330, and compare observational findings to theoretical predictions (on the blackboard, of course).
Abstract
By contrast to coronal X-ray detections, chromospheric emission measures seem to be a less biased indicator for magnetic activity among cool giant stars. We review the legacy of Mount Wilson "S-index" observations, and together with our own chromospheric activity monitoring data of bright, cool giants (obtained by the robotic telescope project TIGRE in Guanajuato, MEX) we put magnetic activity among giant stars into context with stellar evolution.
We show that
(1) despite huge -compared to the Sun- convective envelopes, activity is a common phenomenon among even very evolved cool giants.
(2) After crossing the Hertzsprung Gap, magnetic activity in stars >1.6 M-sun is initialized very strongly. Apart from a first-time convective envelope and not having suffered from magnetic braking before, these foot RGB giants have very fast rotating cores (Beck et al. 2012).
(3) During central Helium burning, giant activity suffers from magnetic braking (as the 4 Hyades K giants demonstrate), much like the cool MS stars.
(4) rising on the AGB, chromospheric emission is, surprisingly, rejuvenated.
More massive giants evolve quicker and are more active. But even Arcturus shows a modest activity and variability. Consequently, we suspect that any evolutionary activity increase coincides in the HRD with faster core contraction.
Abstract
Planetary systems are found to be a very common outcome of the star formation process, but the diversity of planetary architectures is stunning. The analysis of the Solar System as we know it today provides detailed insights into its formation history. One of the major questions in the field of planet formation is how widespread these conditions and history are. In this talk, I will try to address this question based on what we have been and are learning about planet formation based on the study of protoplanetary disks in nearby star-forming regions. I will discuss the constraints on the evolution of solids and volatiles in protoplanetary disks and compare these with what we think were the conditions in the young Solar System. I will also try to highlight the major open questions in the field and where we hope to make progress in the near future.
Video
February 2023
Abstract
The enhanced sensitivity and resolution of modern radio-interferometers have started a new era for both Milky Way and extragalactic studies. However, with the dramatic improvement in sensitivity of interferometers such as ALMA observers face a fundamental challenge: the recovery of extended emission due to the lack of zero-spacing information. Overcoming this problem requires the combination of interferometric plus single-dish observations. In a recent international collaboration, our group investigated the application of state-of-the-art data combination techniques for radio-interferometers. Moreover, we designed novel quality assessment metrics to quantitively estimate the goodness of the data combination process as well as the quality of the resulting data products. Our analysis demonstrate the dramatic improvement of advance data combination techniques with respect to interferometric-alone images. During my talk I will present different performance tests when applying these techniques in both continuum and line ALMA observations.
Abstract
It is generally assumed that Class II sources evolve independently of their surroundings, but many of them are still located near their parent clouds and may continue to interact with them. This may result in late accretion of material onto the disk that can significantly influence disk evolution and planet formation. To study this process systematically, we examined whether proximity to reflection nebulae could be used as a criterion for identifying Class II sources that may be experiencing late-infall. Our results suggest that at least five Class II objects near reflection nebulae have stream-like structures possibly due to late-infall, and a significant fraction of Class II disks in nearby star-forming regions may be undergoing this process. To better understand the impact of the infalling streamers, we are developing a code to quantify the streamer dynamics and thus, constrain the mass infall rates and angular momenta.
Abstract
Most of about 60 known stellar-mass black holes were found in binaries (X-ray binaries and GW mergers). Gravitational microlensing is the only tool capable of detecting single black holes, which are not interacting with anything. I will present our long-term project aiming at discovering and studying the microlensing black holes with the OGLE, Gaia and forthcoming Rubin/LSST surveys. Microlensing non-detections towards the Magellanic Clouds have put strong limits on the compact dark matter content in the Galaxy Halo, while the statistical studies of microlensing events towards the Galactic Centre, revealed a continuum of masses of dark lenses and hint at a lack of the mass gap between neutron stars and black holes.
However, in order to study individual events and obtain the masses of individual lenses it is crucial to measure the size of the Einstein Radius, which defines a separation between the lensed images and is a physical parameter degenerated in the classical microlensing light curve model. This is possible en masse only with the Gaia space mission, which scans the entire sky and is providing not only brightness and colour temporal evolution for nearly 2 billion stars but also positional time series with sub-milliarcsecond precision. I will describe how we search for on-going microlensing events within daily Gaia data using Gaia Science Alerts system and how their photometric, spectroscopic and interferometric follow-up is conducted.
I will present the first candidates for dark lenses from Gaia and then describe how these lessons learnt can be applied to the forthcoming Rubin/LSST survey and GRAVITY+ instrument.
Video
Abstract
FS CMa stars are a subgroup of the B[e] stars. The forbidden emission lines and infrared excess are present in their spectra. This is a sign of very extended circumstellar region. While the B[e] phenomenon has been explained for other B[e] groups, the nature and evolutionary status of FS CMa stars has not been explained. Recently, we discovered very strong magnetic field in one of FS CMa stars, IRAS 17449+2320. The strength of the magnetic field modulus, about 6.2 kG, is in the order of the strongest Ap stars. The magnetic field together with other properties point to the post-merger origin of IRAS 17449+2320. It is very likely that among FS CMa stars other post-mergers are hidden.
The first results of our new N-body simulations show that more than half of mergers occurs in B-type stars. Which means that we are overlooking the most frequent channel of the mergers. This may have important consequence for the enrichment of the ISM by heavier elements. Especially important it may be in the early universe.
Abstract
Over the last decade, our understanding of classical novae has been turned on its head with the discovery of gamma-rays from Galactic eruptions. This discovery has highlighted the value of novae---non-terminal, thermonuclear eruptions on the surfaces of white dwarfs in binary systems---as laboratories for studying shocks and particle acceleration. I will discuss where and how shocks form in the nova ejecta, why we think the shocks may actually dominate the energy budget of the nova eruption, and some of the consequences of the shocks, including dust formation and acceleration of particles to very high (TeV) energies. These recent developments place novae amongst the ranks of interaction-powered transients, making them nearby, common examples of the physics that governs more exotic events like Type IIn supernovae, stellar mergers, and tidal disruption events.
Video
Abstract
The data at the Large Hadron Collider is unique - a trait shared with many large-scale astrophysics and space telescope missions. A key question we ask ourselves is: How can we extract the most science out of this dataset? Despite the huge collaboration size In particle physics we have many more candidate theories we would like to study than analyzers to study them. Each analysis is a data-science mission of its own:
Investigating the data with respect to a single model of new physics can take many PhD-years with the work shared across diverse teams and software scattered around the globe.
In this talk I will talk how about how we can use the principles of Open Data, Reusable and Preserved Software Pipelines as well as AI-driven theory exploration in order to get the most of the LHC data
Abstract
Our success in understanding the baryon cycle of galaxies largely relies on our ability to constrain the physical conditions of their interstellar medium (ISM), out of which the next generation of stars can form. Far-infrared fine-structure lines provide us with a powerful toolset to infer such conditions, both in nearby galaxies and at high-z. These lines are reasonably bright, mostly thin, and not affected by dust obscuration, except in the most extreme cases. With them we can characterize the ionized and neutral gas phases of the ISM, constraining some of their key properties such as the average intensity of the radiation field (G), the density of the gas (nH), and its temperature (Tkin). Photo-dissociation region (PDR) models tell us that the ISM conditions in nearby dusty, star-forming galaxies vary significantly from source to source, for instance changing by orders of magnitude in G/nH. In this talk I will present an array of physical interpretations we can attach to some of the observed correlations seen between emission lines, and as a function of luminosity and luminosity surface density; but since this is an informal discussion, I will also try to highlight some aspects or details of these correlations that I think currently don't have an answer or lack a robust physical interpretation. Hopefully this will trigger minds to help us better understand the reason(s) why we see some of the trends we see in the nearby Universe and apply this knowledge to better interpret galaxies in the distant One.
Abstract
General theory of Relativity, together with some of its postulates (Einstein’s Equivalence Principle and the isotropy of space) can be tested using spectroscopic observations of quasar absorption systems. This can be done by looking for (1) variations of fundamental constants and by (2) measuring the expected systematic redshift drift of the objects at cosmological distances due to the expansion of the Universe.
I will present our projects to perform these measurements using VLT/ESPRESSO observations aided by a newly developed spectral analysis tools based on Artificial Intelligence. The use of the Laser Frequency Comb on ESPRESSO all but removed the known instrumental systematic effects and the application of the AI methods improved the measurement robustness. I will also show the first observations aimed at measuring the redshift drift using the Lyman-alpha forest, jump-starting the future project planned with the Extremely Large Telescope.
Abstract
There is mounting evidence that planetesimals start to form in the disk around Sun-like protostars during the very early evolutionary phases (age < 10^5 years). Observations of young protostellar disks in the Class 0/I stage are thus fundamental to study the initial conditions and the chemical content available for planet formation. Astrochemistry is a powerful tool to investigate the accretion processes taking place in the planet formation region of these embedded objects. In this respect, molecular tracers such as interstellar complex organic molecules (iCOMs) and complex carbon species demonstrated to be more efficient than the standard molecular tracers (CO and its isotopologues) in tracing the disk region and the associated processes, i.e. accretion streamers, shocks, jets. In addition, a striking chemical diversity have been observed between hot corinos sources (enriched in iCOMs) and the WCCC (Warm Carbon Chain Chemistry) sources (enriched of unsaturated small carbon chains). The origin of this diversity is still unclear, as well as its impact on the chemical composition of forming planetary systems. In this talk I will present ALMA observations of iCOMs in young binary systems at high-angular resolution (~ 0.13” corresponding to ~ 40 au). Different molecules trace different spatial distributions, revealing (i) accretion streamers feeding the protostellar disks, and (ii) a chemical differentiation inside the binary system. The study of carbon chains requires lower frequencies, below 50 GHz. In this context, I will also report the results obtained in a pilot study proposed using the 100m Green Bank Telescope to observe several complex carbon chains, in L1544 and IRAS16293-2422, which are the two archetypes of prestellar cores and protostars, respectively. These observations reveal an impressive molecular richness (e.g. C4H, C6H, HC7N, HC9N, C3S) and a chemical differentiation between the two sources at large angular scales. Finally, I will stress the importance of future radio observations (ALMA Band 1, SKA, ngVLA) to image the spatial distribution of the observed carbon chains and to investigate whether large carbon chains and iCOMs coexist in the planet formation region.
Abstract
Public talk, in German.
LIVE STREAMED on the ESO YouTube channel: https://youtube.com/live/wh1mSokTE9s
Abstract
I will show first science results from the MeerKAT Fornax Survey. Our goal is to perform a detailed study of the nearby Fornax galaxy cluster in order to understand how galaxies lose their cold gas and stop forming stars in low-mass clusters (Mvir < 1e+14 Msun). We are doing so through very deep (down to ~1e+18/cm^2) and high resolution (up to ~ 1kpc and 1 km/s) MeerKAT observations of HI gas in a 1x2 Mpc^2 region centred on Fornax.
Our survey started in October 2020 and is now 50% complete. These first data focus on the central region of the Fornax cluster and reveal for the first time the ubiquitous presence of tails and clouds of HI. Some of the HI is clearly being removed from Fornax galaxies as they interact with one another, with the intra-cluster medium and/or with the large-scale gravitational potential. I will present a sample of galaxies with long, one-sided, star-less HI tails (of which only one was previously known) radially oriented within the cluster and with measurable internal velocity gradients. The properties of these tails represent the first unambiguous evidence of ram pressure shaping the distribution of HI in the Fornax cluster.
Video
Abstract
Rest-frame optical emission lines provide a wealth of information about the physics of gas and stars in star-forming galaxies.
For instance, the position of galaxies onto the classical diagnostic diagrams like the “BPT diagrams” are widely used to discriminate between different spectral ionising sources, or to infer the chemical and excitation properties of the ISM.
However, although variations in emission line ratios can be theoretically reproduced by the interplay of many different parameters, it is often difficult to break the degeneracy and disentangle their true relative contribution.
I will present an approach that leverages Machine Learning techniques to identify which physical parameters are the most intrinsically responsible for the observed position of galaxies in different diagnostic diagrams, highlighting strengths and weaknesses, and discussing perspectives in the study of the redshift evolution of galaxy properties from current and future large observational surveys.
Abstract
Women hold a very low portion of professorships in science, such as in chemistry, physics, mathematics, engineering and computer science. Why are women who are talented and dedicated enough to graduate from college not progressing through graduate school and ultimately earning full professorships? Where are these women going, and why do they leave their chosen field?
Much has been written about the underrepresentation of women professors in science, particularly in upper-level positions. Despite the substantial amount of high-quality data on this issue, however, myths and misunderstandings prevail. A frequent claim is that women are derailed by sex discrimination in publishing their work, obtaining grant funding and being hired. However, although these forms of discrimination have played important roles in the past, the current data show that none of these causes can explain today’s underrepresentation.
In this talk, I will review the most recent evidence showing that gender itself is no longer responsible for the current dearth of women in science. I will argue for the importance of another factor in women’s underrepresentation: the choice to become a mother. To place the role of this choice in context, I will consider its impact on women’s careers relative to the impacts of other variables that may reduce women’s participation in the sciences. I will show that recent findings indicate that the effect of children on women’s academic careers is so remarkable that it eclipses other factors in contributing to women’s underrepresentation in academic science.
Key factors that limit women today are still in need of solutions. Understanding the actual cause of women underrepresentation in academy is the first necessary step to create solutions to target the real issue.
Video
Abstract
No new elementary particles have been discovered at the LHC since more than ten years. Does this imply, that collider physics becomes boring in the next decades? My clear answer is no! There are many open questions within the Standard Model which can only be addressed at the LHC in the coming years, potentially opening the door to new physics. Most prominent hints are the recent measurement of the W boson mass at the CDF Experiment as well as the long standing discrepancy of the anomalous magnetic dipole moment of the muon. In this talk, I will give a brief overview of selected and highly exciting results which are expected in the coming years, starting from the properties of the W boson, over the search for axion-like particles to smaller new experiments.
Video
Abstract
In 2021 we started the "Item Identification Project", to look at an ESO-wide approach to configuration & location management of items and products. This topic can affect many aspects at ESO, including procurement, accounting, logistics, storage, manufacturing in our workshop, safety, on-site maintenance and system design, development & engineering.
In this lunch talk, we would like to give you an update on the status of this project. We will start with a short introduction of the topic and why we are working on it, we will look at the recently introduced ESO Item Numbers, and how we updated the various tools (PDM, ERP, MAXIMO, VAULT) at ESO. In the main section of the talk, we will show some concrete examples of the benefits of the newly implemented concepts & tools, how these allow you to more easily find information related to items, and the possibilities for automation to reduce administrative overheads and to let you concentrate on your important tasks.
Abstract
Observations imply that only 5% of the total energy of the universe is in the form of baryonic matter. The remaining 95% is dark matter (e.g. undiscovered particles) and dark energy (e.g. the cosmological constant, a new scalar field of nature). Ongoing and future research is expected to either reveal the nature of the dark sector or revise our fundamental theories. Astronomical observations probe temporal, spatial and energy scales unavailable in terrestrial experiments and are therefore better suited for this purpose. New, advanced astronomical instrumentation is being built to perform unique tests of fundamental physics, complementary to those made using supernovae, the large scale structure, the Cosmic Microwave Background, and gravitational lensing.
I will present how high precision quasar absorption spectroscopy can be used:
(1) to probe new physics by searching for variations in the fundamental constants of physics, and
(2) to directly measure the temporal redshift evolution (redshift drift) of objects in the Hubble flow.
The two projects are also science goals of the Extremely Large Telescope and its ANDES instrument in particular.
January 2023
Abstract
Extragalactic astronomy has made impressive progress in mapping gas around galaxies through both emission and absorption line studies. This can give us valuable insights into the `galactic ecosystem' and provide constraints on gas ejected from and inflowing onto galaxies. At the same time, theoretical models have improved to understand the physical processes at play. However, communications between these two worlds is often not easy and some "translation" of the parameters is required. In my talk, I will focus on Lyman alpha (Lya) emission and "down the barrel" absorption and present tools based on radiative transfer models to be able to fit observations providing physical quantities.
Specifically, I will discuss how parameters from such (simplified) geometries can be degereate and should be interpreted. Time provided, I will also show how these measurements can be combined with other probes such as the spatial variation of the Lya or other resonant lines.
Abstract
Planet formation begins with the coagulation of dust grains in protoplanetary disks. Therefore, constraints on the dust size distribution in the disks can provide a clue to understanding planet formation. Previous studies have estimated the dust size distribution using the spectral index derived from multi-wavelength observations or dust polarization observations. However, these studies give different results depending on their methods and model assumptions and do not reach a consensus.
In this work, we propose another indirect method to constrain the dust size distribution by using the wavelength dependency of the dust ring widths. In many disks, there are dust and gas rings, and larger dust grains are more effectively trapped in the gas rings, forming narrower dust rings. As a result, the dust rings are expected to appear narrower at longer wavelengths since the observations are sensitive to the dust grains whose size is comparable to the observed wavelength.
We analyze high-resolution Band 4 (2.1 mm) and Band 6 (1.3 mm) images of the HD 163296 disk. We find for the first time that the width of the outer dust ring (100 au) appears 1.2 times narrower at the longer wavelength, while the width of the inner ring (67 au) is similar between the two bands. The difference in the ring width depending on the observed wavelength is consistent with the dust trapping scenario in a gas ring. We constrain the maximum dust size a_max and the exponent of the dust size distribution p from the difference in dust ring width between the two bands, together with the spectral index, and found that 1 mm < a_max < 20 mm and p < 3.5 in the inner ring, and a_max > 30 mm and 3.4 < p < 3.6 in the outer ring. These results suggest that the degree of dust growth is spatially dependent, which could affect the formation of planetesimals.
Abstract
Over the past decade hundreds of galaxy candidates have been identified in the Epoch of Reionization (EoR), selected from their rest-frame UV light. Until the advent of ALMA and JWST, only a handful of these sources had spectroscopic redshift determinations and we still have limited understanding of their observational and physical properties. Over the last few years ALMA has already been transforming this field by identifying massive ISM reservoirs at z>6 from bright [CII] line emission, while JWST is now opening up an entire new window onto these first galaxies too.
I will describe how we obtained the first spectroscopic confirmations of galaxies in the EoR with ALMA; pilot studies which led to the execution of the ALMA Large Program REBELS, the first systematic study of luminous galaxies in the Epoch of Reionisation. The ALMA follow-up studies of these programs put new constraints on the dust-buildup, kinematics, and ISM conditions of z~7 galaxies, often finding surprisingly evolved systems. I will discuss some of the surprises that ALMA has uncovered and I will compare and contrast our findings to the newest data from JWST, in order to give insight into what we might expect from the upcoming decade of ALMA+JWST observations.
Video
Abstract
Astronomy has a bright future in the coming decades with (1) state-of-the-art telescopes such as the James Webb Space Telescope and the Extremely Large Telescopes leading to unprecedented in-depth characterization and (2) the multiplication of small ground-based instruments and space missions unlocking large-scale surveys. The field of exoplanets is no exception with intended groundbreaking results on their demography, formation, evolution, chemistry, and potential detections of Earth-like planets and biosignatures. By analyzing the atmosphere of exoplanets, we can determine their chemistry, dynamics, and climate delivering knowledge on the evolution and formation of exoplanets. At high spectral resolution, planetary lines are resolved, which provides more details on the atmospheric structure and their profile informs us on their dynamic (wind patterns, atmospheric escape, …). I will discuss the homogeneous study of the upper atmosphere of 11 exoplanets observed with SPIRou through the near-infrared helium triplet. Finally, I will outline the NIRPS spectrograph (operations starting April 1st) and the objectives of its consortium as well as their 725 nights of guaranteed time observations.
Abstract
The Imaging X-ray Polarimetry Explorer (IXPE), a NASA/ASI mission, is the first satellite dedicated to study the polarization of cosmic sources in the X-ray band. Launched in December 2021, in its first year of operation is providing several very interesting - and in some cases rather surprising - results on many different classes of X-ray sources.
In this talk, the mission will be described and the most important results discussed.
Video
Abstract
ERIS is a new Adaptive Optics (AO) instrument installed at the Cassegrain focus of VLT-UT4 in January 2022 and led by a Consortium of Max-Planck Institut fuer Extraterrestrische Physik, UK-ATC, ETH-Zurich, NOVA-Leiden, ESO and INAF. The ERIS AO system provides NGS mode to deliver high contrast correction and LGS mode to extend high Strehl performance to large sky coverage. The AO module includes one 40x40 LGS wavefront sensor (WFS), one NGS WFS able to switching between 40x40 and 4x4 configuration, the related optics to relay the telescope beam and a dedicated SPARTA real time computer running the AO loop up to 1kHz. The AO module, with the 1170-actuator Deformable Secondary Mirror and the Laser Facility from VLT-AOF, provides AO correction to the high resolution coronagraphic imager NIX (1-5um) and the IFU spectrograph SPIFFIER (1-2.5um). In this talk we briefly review the ERIS AO system design and we present the AO results from ERIS commissioning that was held in the period February to November 2022.
Abstract
The Pre-Main-Sequence stellar evolution is shaped by the mass accretion process. In recent years, we discovered the variable nature of the mass accretion process on embedded young star objects (YSOs). High-amplitude irregular accretion bursts were observed across all wavelengths on timescales from months to decades, which are triggered by various instabilities throughout the accretion disc. On the other hand, periodic accretion bursts were discovered among a group of embedded YSOs, which might be consequences of dynamical perturbations in young binary or star-planet systems. In the first part of the talk, I will present our latest search results on long-term eruptive YSOs from the decade-long near-IR VVV survey, including 15 new FUor-type objects. In the second part, I will briefly present our latest publication on periodic outbursting YSO candidates that provides indirect evidence of early planet/companion formation.
Abstract
The unified scheme explains the differences between type I and II AGNs by the different orientation of an optically thick torus relative to the observer. The dynamics in such a torus was unclear due to the relative small scale of these objects. The unprecedented resolution of ALMA has recently allowed us to improve significantly the information about dynamics of clouds in the obscuring tori for some AGNs. On this ground, we present our N-body simulations of the toroidal structure of clouds moving around a supermassive black hole (SMBH). We apply ray-tracing algorithm to account for the effects of obscuration of the central engine by the clouds. As a result, we obtain the velocity and temperature maps which allow us to interpret the ALMA and VLTI observations. We also estimate the SMBH masses in the nearest Sy2 galaxies and provide an explanation of the counter-rotation of the torus in NGC 1068.
Abstract
The most pressing unknowns in fundamental physics - the nature of dark energy, dark matter, neutrinos, and cosmic ination - imprint clues of their nature onto the spatial distribution of and gravitational lensing effect experienced by distant galaxies. Our ability to observe large galaxy samples is exponentially increasing, with next-generation instruments like DESI, Euclid and the Vera Rubin Observatory able to image billions and record spectra of tens of millions of galaxies. I will cover ways of nding cosmological needles in such big-data haystacks, highlighting results from the latest round of Dark Energy Survey analyses. I will also discuss roles articial intelligence can take, both as a tool for enabling accurate (not just precise) analyses, and as a model for the complex systems found in the universe that enables their use as cosmological probes.
Abstract
GRAVITY+ Adaptive Optics (GPAO) is implementing high order (40x40), laser-assisted, single-conjugated correction into each of the four Unit Telescopes of Paranal observatory. This transformative upgrade will boost the efficiency of the single-mode instruments of VLTI by a large number (new Kband limiting mag >20), it will multiply the sky coverage by several orders of magnitude and unlock many types of object previously impossible to reach with optical interferometry (e.g high-redshift galaxies), and it should unveil several exoplanets as close as <100mas thanks to the “interferometric differential imaging” capability provided by the coherent nature of the four beams.
Abstract
Climate change is one of the biggest threat modern generations have to face. To ensure a liveable future, urgent measures should be taken. One of the best ways to obtain such quick change in our society is by informing citizens, to engage them, and try to reach the social tipping point as fast as possible.
I will introduce the PLEES index. This index is based on Maslow's hierarchy of needs and is projected under different climate change scenarios, to quantify the psychological, social, and economical impact of climate change in the world.
This index is a visual tool, easily distributable in social medias, aiming to inform people about climate change, targeting wealthier European countries, with financial and political means to generate a positive change, showing that their life comfort is at risk.
Our working group in Vienna believe that popularising the idea of social tipping point is a good way to show that big changes can happen very fast if citizens act together.
Abstract
Most galaxies comparable to or larger than the mass of the Milky Way host hot, X-ray emitting atmospheres and central radio sources. Hot atmospheres and radio jets and lobes are the ingredients of radio-mechanical active galactic nucleus (AGN) feedback. At least half of the most massive early type galaxies harbour multi-phase filamentary gas, which appears to result from the thermally unstable cooling of their hot atmospheres. We will present recent results based on radio and X-ray observations, which indicate that in massive early type galaxies the central radio sources are mostly switched on. We will show that for galaxies with thermally unstable hot atmospheres, the mechanical jet power correlates strongly with the Bondi accretion power. Further investigating the dependence of jet power on individual quantities in the Bondi formula, such as the supermassive black hole mass and the specific entropy of the gas at the Bondi radius, we find a very tight correlation between the jet power and black hole mass and, although poorly constrained, a hint of an anti-correlation between jet power and entropy. The results indicate that at least for thermally unstable systems, the jet power is set primarily by the supermassive black hole mass. The fact that we only see a strong correlation for thermally unstable atmospheres suggests that the black holes producing the jets and lobes are fed by cooling gas from the galactic atmospheres. It appears that once the atmosphere becomes thermally unstable, the cooling gas feeds the black holes in the centres of all galaxies at a similar jet-to-Bondi power ratio, possibly indicating a key universal property of black hole accretion in early-type galaxies. Importantly, since the central black hole mass of X-ray luminous early-type galaxies correlates with the total mass of the host halo, more massive systems undergoing thermally unstable cooling will naturally have larger jet powers.
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