Star clusters are gravitationally bound stellar systems commonly formed in star formation events. These systems form in the densest regions of giant molecular clouds and host the majority of the massive stars forming in these regions. A quick look at the cluster population in our Milky Way already proves that these bound stellar systems have continuously formed during the assembly history of our own galaxy, as witnessed by globular clusters, open clusters, young star clusters. I will present some key results that relates the most recent efforts to link the statistical properties of cluster populations in local galaxies (i.e. mass functions, dissolution time scales, formation efficiency) to the global physical properties of galaxies, such has star formation per unit area, gas surface density, and dynamics.

I will show how key events for galaxy evolution, such as mergers or increased gas fraction change the properties of the stellar clusters formed during these enhanced star formation events, therefore making them tracers of the assembly history of galaxies. I will conclude presenting some ongoing analyses where we evaluate the effect of clustered stellar feedback on their immediate surroundings and at galactic scales showing that star clusters are fundamental components of the star formation cycle of galaxies.

Characterising the relationship between stars, gas, and metals in galaxies is a critical component of understanding the cosmic baryon cycle. This review compiles contemporary censuses of the baryons in collapsed structures and their chemical make-up and dust content. The HI mass density of the Universe as well as new observations of molecular hydrogen provide fresh clues on the cosmic cold gas depletion timescale and the cause of the star-formation history decline at low-redshift. The census of the metals in various phases from z=0 to z~5 permits to revisit the 20-year old "missing metals problem". Lastly, I will present new calculations of the cosmological dust mass density in the neutral gas up to z~5. Together, the cosmic evolution of baryons, metals, and dust is —in the broadest strokes— now fairly secure.

The centers of massive galaxies are special in many ways, not least because apparently all of them host supermassive black holes. Since the discovery of a number of relations linking the mass of this central black hole to the large scale properties of the surrounding galaxy bulge it has been suspected that the growth of the central black hole is intimately connected to the evolution of its host galaxy. However, at lower masses, and especially for bulgeless galaxies, the situation is much less clear. Interestingly, these galaxies often host massive star clusters at their centers, and unlike black holes, these nuclear star clusters provide a visible record of the accretion of stars and gas into the nucleus.

I will present our ongoing observing programme of the nearest nuclear star clusters, including the ones in our Milky Way and the Sagittarius dwarf galaxy. These observations provide important information on the formation mechanism of nuclear star clusters, allow us to measure potential black hole masses and give clues on how black holes get to the centres of galaxies.

The kinematics of high redshift galaxies reveals important clues on their formation and assembly, providing also strong constraints on galaxy formation models. However, studies of high-z galaxies are strongly affected by two observational limitations: the angular resolution and the signal-to-noise ratio. Gravitational lensing provides a unique tool to study the internal motions of high-z galaxies, thanks to the increase in sensitivity and angular resolution provided by the magnifications.

In this talk, I will present the dynamical properties of a sample of strongly gravitationally lensed dusty star-forming galaxies (DSFGs) at z ~ 4 on sub-kpc scales, obtained using ALMA observations of the [CII] emission line. The rotation curves of these galaxies demonstrate that at least some young galaxies are dynamically akin to those observed at low redshift, and only weakly affected by the extreme physical processes that characterize the early Universe. I will then show some preliminary results on the study of the evolutionary connection between the population of high-z DSFGs and the local early-type galaxies.

In recent years there have been big advances in women taking up scientific and technological studies and joining the workforce in those areas. However, in fields such as Physics, Engineering and Informatics women are still under-represented, already at the undergraduate level. In order to help achieve full and equal participation in science by women, to recognize their achievements and to promote career perspectives in science among girls and young women many initiatives have been put in place around the world. "Habla con ellas - Mujeres en Astronomia", lead by the IAC in Tenerife, is aimed for Spanish educational Centres of all types and levels, with the goal to promote the role of women in science and to encourage scientific and technological vocations among girls as well as boys. In this lunch talk I will present the initiative and discuss my personal experience as a member of the group of female astronomers participating in it, focusing on the aspect of gender stereotypes.

I will provide a first glimpse of the PHANGS project which encompasses three main observational large programmes with MUSE/VLT, ALMA and HST to probe star-forming disc galaxies at cloud-scales. After providing a bit of context and some details of the associated on-going observational and theoretical efforts, I will briefly review a few recent and coming scientific results. The focus of this talk will be the scale-coupling between disc dynamics and star formation, while touching on other ingredients (e.g., the distribution of metals) which should help us constrain the build-up and evolution of main-sequence galaxies.

With the aim of characterizing the role played by magnetic fields in the formation of young protostars, several recent studies have revealed unprecedented features toward high angular resolution ALMA dust polarization observations of Class 0 protostellar cores. Especially, the dust polarization has been found to be enhanced along the cavity walls of bipolar outflows, which are subject to high irradiation from the reprocessed radiation field emanating from the central protostar. In addition, highly polarized dust thermal emission has been detected in regions most likely linked with the infalling envelope, in the form of filamentary structures being potential magnetized accretion streamers. These observations allow us to investigate the physical processes involved in the Radiative Alignment Torques (RATs) acting on dust grains from the core to disk scales. Notably, we propose that the polarized emission we see at millimeter wavelengths along the irradiated cavity walls can be reconciled with the expectations of RAT theory if the aligned grains present in these cavities have grown larger than what is typically expected in young protostellar cores. To approach an estimation of the efficiency of dust alignment in protostars, we gathered all the available ALMA dust polarization observations of Class 0 protostars, to perform a statistical analysis examining the trend between the dispersion of polarization position angles S, and the fractional polarization P_frac.

We report a significant correlation between S and P_frac, whose power-law index differs significantly from the one observed by Planck in star-forming clouds. The grain alignment efficiency is surprisingly constant across three orders of magnitude in envelope column density. Synthetic observations of non-ideal magneto-hydrodynamic simulations of protostellar cores implementing RATs, show that the ALMA values of grain alignment efficiency lie among those predicted by a perfect alignment of grains, and are significantly higher than the ones obtained with RATs. Ultimately, our results suggest dust alignment mechanism(s) are efficient at producing polarized dust emission in the local conditions typical of Class 0 protostars. The grain alignment efficiency found in these objects seems to be higher than the efficiency produced by the standard RAT alignment of paramagnetic grains. Further study will be needed to understand how more efficient grain alignment via, e.g., different irradiation conditions, dust grain characteristics, or additional grain alignment mechanisms can reproduce the observations, allowing further constraints on dust grain evolution in young cores.

In this talk, I will give an overview of what we have learned from comparing the emission from stars, dust and molecular gas in z~2 star-forming galaxies. Over the last few years sub-mm interferometers have revolutionised our view of the cool, molecular ISM at high redshift. Large surveys, probing the CO and/or dust continuum emission with ALMA and NOEMA, have provided a statistical view of the evolution of the molecular gas content. Now, "resolved" sub-/mm observations are beginning to probe the spatial extent of the molecular gas in high-redshift galaxies via these tracers. But do the dust-continuum and CO emission paint the same picture of molecular gas at high redshift? Recent studies of dust-rich galaxies indicate that the CO and dust continuum emission may arise from different regions, with the dust emission at least twice as compact as the stellar or CO emission. We investigate whether this also holds for extended galaxies, selected based on their bright CO emission. In this talk I will describe what we learnt from our "high-resolution" ALMA observations of three extended galaxies in the HUDF and what the implications are for comparing stars and molecular gas at z~2 in the coming decade.

Recent ALMA studies find the existence of ~10-15 kpc scale [CII] 158um line halo surrounding early galaxies in deep stacking measurements. Individual experiments are essentially required further to understand the origin of the [CII] halo. Here we present the physical extent of [CII] line-emitting gas from 46 star-forming galaxies at z=4-6 from the ALMA Large Program to INvestigate CII at Early Times (ALPINE). Using exponential profile fits, we measure the effective radius of the [CII] line (r e,CII) for individual galaxies and compare them with the rest-frame ultraviolet (UV) continuum (r e,UV) from Hubble Space Telescope images. The effective radius r e,CII exceeds r e,UV by factors of ~2-3, and the ratio of r e,CII/r e,UV increases as a function of Mstar. We identify 30% of isolated ALPINE sources as having the > 10-kpc scale [CII] halo detected at 4.1-10.9sigma beyond the size of rest-frame UV and FIR continuum. One object has tentative rotating features up to ~10 kpc, where the 3D model fit shows the rotating [CII]-gas disk spread over 4 times larger than the rest-frame UV-emitting region. Galaxies with the extended [CII] line structure have high star formation rate, high stellar mass (Mstar), low Lya equivalent width, and more blueshifted (redshifted) rest-frame UV metal absorption (Lya line), as compared to galaxies without such extended [CII] structures. Although we cannot rule out the possibility that a selection bias toward luminous objects may be responsible for such trends, the star-formation-driven outflow also explains all these trends. In the talk, I will discuss the possible origins of the [CII] halo, including predictions from the latest theoretical simulations.

Cold gas and cosmic dust are the fuel of star formation. ALPINE is an ALMA Large Programme which has built the first statistically representative sample of star-forming galaxies at z>4 by targeting emission from singly ionized carbon [CII] at 158 μm, which traces both emission from star-forming regions and molecular hydrogen gas clouds, and the thermal continuum from dust at the end of the epoch of reionisation (4.4 < z < 5.9). Observations by the ALPINE team have revealed that a significant fraction of the star formation at this epoch is already hidden by dust clouds. ALPINE observations have also shown how unruly these young galaxies were by finding a large fraction of disturbed morphologies and ubiquitous gas outflows.

Formamide (NH2CHO) is an important prebiotic molecule that has been detected in many different interstellar environments, but there is disagreement about the dominant method for its formation. In the past few years, sub-millimetre observers have taken up the task of trying to understand the formation of formamide observationally. I have chosen high- and low-mass star forming regions as the ideal laboratory to study the relationship between formamide and its potential precursors. In my talk, I will give a detailed overview of this problem, present my recently published work, and show my preliminary new results.

Classical T Tauri stars (cTTs) are pre-main sequence stars surrounded by an accretion disk. They host a strong magnetic field, and both magnetospheric accretion and ejection processes develop as the young magnetic star interacts with its disk. Studying this interaction is a major goal toward understanding the properties of young stars and their evolution. During this talk, I will present the analysis of the accretion process in the young stellar system HQ Tau, an intermediate-mass T Tauri star (1.9 Msun). The time variability of the system is investigated both photometrically, using Kepler-K2 and complementary light curves, and from a high-resolution spectropolarimetric time series obtained with ESPaDOnS at CFHT. The quasi-sinusoidal Kepler-K2 light curve exhibits a period of 2.424 d, which we ascribe to the rotational period of the star. The radial velocity of the system shows the same periodicity, as expected from the modulation of the photospheric line profiles by surface spots. A similar period is found in the red wing of several emission lines (e.g., HI, CaII, NaI), due to the appearance of inverse P Cygni components, indicative of accretion funnel flows. Signatures of outflows are also seen in the line profiles, some being periodic, others transient. The polarimetric analysis indicates a complex, moderately strong magnetic field which is possibly sufficient to truncate the inner disk close to the corotation radius, rcor∼3.5 Rstar. Additionally, we report HQ Tau to be a spectroscopic binary candidate whose orbit remains to be determined. The results of this study expand upon those previously reported for low-mass T Tauri stars, as they indicate that the magnetospheric accretion process may still operate in intermediate-mass pre-main sequence stars, such as HQ Tau.

I present a new suite of simulations that resolve individual molecular clouds down to ~0.1 pc scales while they are embedded within a Spiral Galaxy. This uniquely enables us to study fragmentation and star formation within the resolved clouds in their true galactic context for the first time and is a perfect point of comparison to ISM observations in the ALMA era. Our Arepo simulations include a time-dependent chemical model, gas self-gravity, the ISRF and gas self-shielding, magnetic fields, sink particles, supernova feedback, and photo-ionisation from sinks. Using an analytic Milky-Way like spiral potential as our base, we turn on these effects step-by-step in a series of simulations to create a laboratory for testing the physics of the ISM and star formation from kpc scales to cold cores.

The molecular clouds formed in our galaxy scale simulations consist of networks of velocity coherent filaments, as seen in observations. In regions with high turbulence from supernova feedback the filaments within the clouds are shorter and less aligned than those in more quiescent regions dominated by the galactic potential. Stars form in all cases, but are more likely to form at the junctions of filaments in the feedback dominated case.

To investigate how the turbulence driven by the large-scale forces compares to observations we perform non-LTE line transfer to calculate the CO emission, and then compare to observed data using PCA and the Turbustat package. A good match to observed size-linewidth relations is found only when there is both self-gravity and previous turbulent mixing from supernova.

I will then investigate how different magnetic field strengths impacts on the formation of molecular clouds, the star formation rate given by sink particles, and the orientation of filamentary structures. Finally, I will show early results extending our Cloud Factory simulations to low metallicity dwarf galaxies.

Dwarf galaxies are powerful tools of near-field cosmology and galactic archaeology: their numbers, distribution, and star formation can be linked to both the tenets of LCDM (the missing satellite "problem," their (an)isotropic distribution, their dark matter content) and to the build-up of their hosts and their environment (accretion, quenching). The exquisite detail offered by observation of the nearby Milky Way dwarf galaxies has built a picture of what dwarf galaxies are and how they evolved through time. In this talk, I will review the increasingly sharp view we are building of the dwarf-galaxy system of the Milky Way's "sister" galaxy, Andromeda, and emphasize key similarities and differences between these two systems of satellites in the hope to learn what features are common or, on the contrary, driven by the different pasts of the Milky Way and Andromeda.

The Event Horizon Telescope (EHT) is a global effort to construct an Earth-sized virtual radio telescope array, with the ultimate goal to actually make pictures and movies of two nearby low luminosity supermassive black holes. The initial results of the first full EHT observing run in 2017 were presented on 10 April 2019. A detailed theoretical understanding of black hole astrophysics is now very crucial to interpret these observations. The focus of the talk is on observing and modeling polarimetric properties of light produced in synchrotron processes in plasma falling towards the event horizon.

The polarized component of light gives us detail constraints on the magnetic field geometry and dynamics at the event horizon, which are keys to understand the accretion, jet launching process and black hole energy extraction.

Globular Clusters are ideal laboratory to study both stellar evolution and dynamics. In this talk I will describe two empirical methods (i.e. the study of the radial distribution of the population of Blue Straggler Stars and the slope of the Mass Function of the Main Sequence stars) to infer the dynamical age of clusters.

The extreme ultraviolet (EUV) spectra of distant star-forming regions cannot be probed directly using either ground- or space-based telescopes due to the high cross-section for interaction of EUV photons with the interstellar medium. This makes EUV spectra poorly constrained. The mm/submm recombination lines of H and He, which can be observed from the ground, can serve as a reliable probe of the EUV.

Here we present a study based on ALMA observations of three Galactic ultra-compact HII regions and the starburst region Sgr B2(M), in which we reconstruct the key parameters of the EUV spectra using mm recombination lines of HI, HeI and HeII. We find that in all cases the EUV spectra between 13.6 and 54.4 eV have similar frequency dependence: L_nu~ nu^{-4.5 +/- 0.4}. We compare the inferred values of the EUV spectral slopes with the values expected for a purely single stellar evolution model (Starburst99) and the Binary Population and Spectral Synthesis code (BPASS). We find that the observed spectral slope differs from the model predictions. This may imply that the fraction of interacting binaries in HII regions is substantially lower than assumed in BPASS. The technique demonstrated here allows one to deduce the EUV spectra of star forming regions providing critical insight into photon production rates at lamda < 912 A and can serve as calibration to starburst synthesis models, improving our understanding of star formation in distant universe and the properties of ionizing flux during reionization.

It is well established that AGN take an active part in shaping the way the Universe looks. In particular, AGN feedback is a key ingredient in galaxy formation models and is now widely considered to be one of the main drivers in regulating the growth and assembly of massive galaxies. In my talk I will describe several efforts in our group to understand the power, reach and impact of AGN feedback processes and how they impact the build-up of galaxies and structures across cosmic time.

Using the SDSS-IV MaNGA survey at low redshift, we have found that AGN signatures and winds can be easily hidden in the integrated spectrum of a galaxy. We have therefore developed a new AGN selection tailored to IFU data uncovering a more nuanced picture of AGN activity allowing to discover AGN signatures at large distances from the galaxy center. Our measurements demonstrate that high velocity gas is more prevalent in AGN and that outflow and feedback signatures in low-luminosity, low-redshift AGN may so far have been underestimated. At higher redshift, we have found — by relating feedback signatures in powerful quasars to the sSFR in their hosts — that outflows can indeed suppress star formation in their hosts, consistent with the AGN having a `negative' impact. Feedback signatures seem to be best observable in gas-rich galaxies where the coupling of the AGN-driven wind to the gas is strongest. However, both star formation and quasar activity peaks at z ~ 2-3 where AGN are expected to impact the build-up of stellar mass the most. Our team recently discovered a unique population of luminous high-redshift (2 < z < 4) extremely red quasars (ERQs) in the SDSS-III/BOSS and WISE surveys with extreme outflow properties, including blueshifted [OIII] lines at speeds up to 6000 km/s and unusual Lya profiles. The nature of the Lya emission in ERQs is especially intriguing, as it might be tracing quiescent filaments on halo scales or dusty, very clumpy, highly accelerated gas filaments close to the nucleus. ERQs are therefore the ideal population to obtain a census of the overall mass and energy budget of both outflow and infall/feeding from the CGM, an essential requirement to probe the detailed and full feedback loop.

Building on these results, I will also introduce the JWST ERS Program "Q3D" (PI: Wylezalek) which will make use of the IFU capabilities of NIRSpec and MIRI and through which we will study the impact of three carefully selected luminous quasars on their hosts. Our program will provide a scientific dataset of broad interest serving as a pathfinder for JWST science investigations in IFU mode.

The Galactic Center region, including the nuclear disk, has until recently been largely avoided in chemical census studies because of extreme extinction and stellar crowding. Large, near-IR spectroscopic surveys, such as the Apache Point Observatory Galactic Evolution Experiment (APOGEE), allow the measurement of metallicities in the inner region of our Galaxy. Making use of the latest APOGEE data release (DR16), we are able for the first time to study cool AGB stars and supergiants in this region. The stellar parameters of five known AGB stars and one supergiant star (VR 5-7) show that their location is well above the tip of the RGB. We study metallicities of 157 M giants situated within 150 pc of the Galactic center from observations obtained by the APOGEE survey with reliable stellar parameters from the APOGEE/ASPCAP pipeline making use of the cool star grid down to 3200 K. Distances, interstellar extinction values, and radial velocities were checked to confirm that these stars are indeed situated in the Galactic Center region. We detect a clear bimodal structure in the metallicity distribution function, with a dominant metal-rich peak of [Fe/H] ∼ +0.3 dex and a metal-poor peak around [Fe/H] = −0.5 dex, which is 0.2 dex poorer than Baade’s Window. The α- elements Mg, Si, Ca, and O show a similar trend to the Galactic Bulge. The metal-poor component is enhanced in the α-elements, suggesting that this population could be associated with the classical bulge and a fast formation scenario. We find a clear signature of a rotating nuclear stellar disk and a significant fraction of high velocity stars with vgal > 300 km/s; the metal-rich stars show a much higher rotation velocity (∼ 200 km/s) with respect to the metal-poor stars (∼ 140 km/s). The chemical abundances as well as the metallicity distribution function suggest that the nuclear stellar disc and the nuclear star cluster show distinct chemical signatures and might be formed differently.

I will report evidence from the APOGEE survey for the presence of a new metal-poor stellar structure located within ~4 kpc of the Galactic centre. Characterised by a chemical composition resembling those of low mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ~5 x 10^8 Mo, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H]<-0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

Current models of galaxy formation widely agree on the key importance of star formation-driven outflows in regulating the evolution of galaxies across the cosmic time, although observational evidence is still limited to local and intermediate-redshift galaxies. I will present recent pilot studies of the galactic feedback efficiency in the Early Universe, exploiting observations of a large sample of normal star-forming galaxies at z~4-6, drawn from the "ALMA Large Program to INvestigate [CII] at Early times" (ALPINE) survey. Our findings suggest that outflows, strong dynamical interactions and gas exchanges with the circumgalactic medium are at work in regulating the baryon cycle of normal galaxies already at very early epochs.

M82 X-2 is the first discovered pulsating ultraluminous x-ray source (PULX), and the one with the shortest orbital period. The luminosity of PULXs seems to imply a highly super-Eddington mass accretion rate, and M82 X-2 is the one where this hypothesis can be tested more easily over time, due to its very well constrained orbital parameters and timing behavior. I will give an overview on PULXs, describe the quest for these rare and fascinating objects, and go through the current models of PULXs and possible ways to test these models thanks to recent observations of M82 X-2.

Our understanding of the Milky Way is now undergoing a revolution, thanks to the European Space Agency Gaia mission. The Gaia second data release (GDR2, Gaia Collaboration et al. 2016) has uncovered a living and breathing Galaxy, out of equilibrium, with an eventful history, rich in accretion events and interactions with satellite galaxies.

Gaia's ability to trace the motion of stars in the sky is producing a moving picture that is deeply transforming our Milky Way's understanding. In this talk, I will focuss on the reconstruction of the merger tree from chemo-dynamical diagnostics. In particular, the study of heavy elements has recently revealed a chemo-dynamical correlation for both globular clusters and field stars of the Galactic halo involving their [Y/Eu] abundance and orbital inclination. The detected trends, likely imprinted by the Milky Way's formation history, shed light into the halo heavy element abundance scatter, challenging chemical evolution models. [Y/Eu] under-abundances typical of protracted chemical evolutions, are preferentially observed in the slow rotating merger debris around the Galactic polar axis. This embodies a mixture of accretion remains from satellites of different masses, pointing to a possible preferential merger
direction, crucial to constrain simulations of the Local Group.

I will present a work based on deep multi-band (g, r, i) data from the Fornax Deep Survey with VST. In this work we analyse the surface brightness profiles, as well as the color profiles of the 19 bright ETGs inside the virial radius of the Fornax cluster, with the main aim of identify signatures of accretion onto galaxies by studying the presence of outer stellar halos, and understand their nature and occurrence. This analysis also provides a new and accurate estimate of the intra-cluster light inside the virial radius of Fornax.

We find that in the most massive and reddest ETGs the fraction of light in, probably accreted, halos is much larger than in the other galaxies. Less-massive galaxies have an accreted mass fraction lower than 30%, bluer colours and reside in the low-density regions of the cluster. Inside the virial radius of the cluster, the total luminosity of the intra-cluster light, compared with the total luminosity of all cluster members, is about 34%. Inside the Fornax cluster there is a clear correlation between the amount of accreted material in the stellar halos of galaxies and the density of the environment in which those galaxies reside. By comparing this quantity with theoretical predictions and previous observational estimates, there is a clear indication that the driving factor for the accretion process is the total stellar mass of the galaxy, in agreement with the hierarchical accretion scenario.

Galaxies are constantly fed by the diffuse material from the intergalactic medium through the Circum-Galactic Medium (CGM). We can probe these vast gaseous halos around galaxies by studying absorbers detected in the spectra of bright background quasars. To understand the dynamics of the system we combine the physical properties from the absorption features with the broader view of the absorber’s host and its environment by emission diagnostics, using IFU spectroscopy. Gas travelling through the CGM enters a galaxy and replenishes the gas reservoirs which further transforms into molecular phase - the direct fuel of the star formation. Recent studies have suggested a possible link between the cosmic density of H2 - the most abundant molecule in the Universe - and the Star Formation History of the Universe. The second most abundant molecule, still linked to star formation, is CO and its rotational transitions are bright and relatively easy to observe with ALMA, allowing us to probe the molecular content of whole populations of galaxies.

In my talk, I will present the two surveys probing the gaseous content of galaxies in different phases: molecular within the galaxies and diffuse in the CGM. We combined MUSE and ALMA to understand the properties of host galaxies of quasar absorbers in the MUSE-ALMA Haloes Survey. Surprisingly, we found large fraction of groups associated with absorbers, which introduces a challenge in connecting CGM detected in absorption to a particular galaxy. Addressing the molecular gas content of galaxies, we turned towards the archival observations of ALMA calibrators, constructing ALMACAL-CO, blind CO emission-line survey. A survey is a part of the extensive science project ALMACAL, utilizing ALMA calibration data for scientific purposes. Thanks to a uniqueness of the ALMACAL dataset we are able to study galaxies over a wide area, and are not sensitive to the effects of cosmic variance. The results of the survey, confirm findings of other blind emission line searches: the shape of the molecular gas mass function mirrors star formation history of the Universe, suggesting that the molecular gas content of galaxies is closely linked to the evolution of SFH.

Precise measurements of Cosmic Microwave Background (CMB) temperature anisotropies opened an unprecedented window on the primordial Universe. The next frontier in CMB science is the detection of polarisation B-modes, sourced by primordial gravitational waves emitted during inflation. Detecting B-modes would therefore be a smoking gun for inflation, a theory which awaits confirmation for almost 40 years!
 
However, this detection is particularly difficult because the primordial B-modes signal is very low, and is moreover shadowed by various sources of galactic and extra-galactic contamination: polarised dust, synchrotron radiation, weak gravitational lensing,…To achieve this, the next generation of CMB polarisation experiments needs not only to reach an unprecedented raw instrumental sensitivity, but also to be able to distinguish the B-modes signal from these contaminations. This calls for enhanced detection capabilities, new technologies, as well as novel data analysis methods.
 
In this talk, I will review challenges in B-modes detection, and present recent instrumental progress in CMB polarisation experiments and methods to efficiently clean the B-modes signal from spurious contamination.

We are made of stardust—or, at least in significant parts, of material processed in stars. Hot, massive giant stars can drive the chemical evolution of galaxies and trigger and quench star formation through their strong winds and their final demise as supernovae. Yet optical and X-ray measurements of the wind mass loss strongly disagree and can only be reconciled if the winds are highly structured, with colder, dense clumps embedded in a tenuous hot gas. In (quasi-)single stars, however, wind properties are inferred for the whole wind ensemble only; no measurements of individual clumps or clump groups are possible, limiting our understanding of wind properties. Luckily, nature provides us with perfect laboratories to study clumpy winds: high mass X-ray binaries.

X-ray binaries are systems where a black hole or a neutron star accretes matter from the wind of a stellar companion. In high mass X-ray binaries, the companion is a massive supergiant and the compact object accretes material from its wind. The stellar wind drives changes in the accretion and thus the X-ray emission from the compact object. But the point-like X-ray source can also be used as an in-situ probe of the wind and enables us to study the large and small scale wind structures as well as the wind's interaction with the compact object.

In this talk, I will give an overview over wind studies with high mass X-ray binaries. I will then focus on two of the brightest high mass X-ray binaries, Cygnus X-1 and Vela X-1, with, respectively, a black hole accreting from an O-type star and a neutron star from a B-type star. In particularly, I will show how we can use low resolution high orbital cadence observations to constrain the intrinsic clumpy structure of the stellar wind and how time-resolved high resolution observations reveal the properties of both, the hot intra-clump medium and denser, colder wind clumps.

Structure evolution is now understood to be the products of a Hubble time's worth of merging, accretion, and interaction with the surrounding environment. This history is hidden, however, being quickly mixed into a smooth and, apparently, featureless distribution of baryons, or by being at surface brightness much fainter than the sky. The synergy between bright tracers, like Globular Clusters (GCs) and Planetary Nebulae (PNs), and multi-frequency data can solve both of these observational challenges allowing us to investigate the region in space where galaxy halos blend into the intra-cluster component (ICC), a direct product of the interactions within a cluster.
 
The focus of this talk will be on the nearby Virgo cluster where GCs and PNs have shown that the galaxy halos and the ICC are dynamically distinct with different parent stellar populations and progenitors. Finally, I will talk about some recent studies that used the wealth of multi-frequency data to detect for the first time diffuse intra-cluster dust in Virgo transported in the intra-cluster space through ram pressure and tidal stripping phenomena.

Clumpy rest-frame UV morphologies are ubiquitous among z=1-3 star-forming galaxies. We show that the stellar mass medians derived for different clump samples can vary by two orders of magnitude from 10^7 Msun to 10^9 Msun, depending on the spatial resolution and depth of the data analysed and the clump detection limit applied. To derive intrinsic clump masses and sizes in a prototypical clumpy galaxy, we have undertaken a detailed analysis of the Cosmic Snake at z=1.036. The Cosmic Snake is an exceptional gravitationally lensed clumpy galaxy, where we reach a significantly improved depth and unprecedented physical scale of 30-70 pc. The identified UV-bright clumps in the Cosmic Snake have masses spread between 10^6-10^8.5 Msun and radii between 35-300 pc. The comparison with the moderately amplified counter-image of the Cosmic Snake with a 300~pc resolution enables us to demonstrate that clumps are blended already at this resolution, but that the stellar mass of these blends overestimates the true clump mass at most by a factor of 5. As a result, it is the sensitivity threshold used for the clump selection that has the higher effect on the inferred masses, biasing the detection of clumps at the low-mass end, as also confirmed by our Halpha mock observations obtained from post-processed simulations of clumpy disk galaxies. Based on these findings, we compile a sample of the less affected clumps by sensitivity and spatial resolution effects currently known at z~1-3. We use this sample to obtain the first constraints on the mass function of high-redshift stellar clumps, which is found to be consistent with a power-law distribution of slope ~ -2, similarly to the young star clusters in nearby galaxies. This suggests that high-redshift clumps form under different gas conditions, but in a similar fashion to star clusters we see today. This is further confirmed by our ALMA CO(4-3) observations of the Cosmic Snake, which reveal 17 giant molecular clouds (GMCs). These GMCs are clearly different from their local analogues, being offset from the Larson scaling relations. We argue that GMCs must inherit their physical properties from the ambient ISM particular to the host galaxy. The measured large GMC masses demonstrate the existence of parent gas clouds with masses high enough to allow the in-situ formation of similarly massive stellar clumps seen in the Cosmic Snake galaxy in a comparable number to the GMCs. The comparison of the GMC masses and star cluster masses suggests a high efficiency of star formation, which anchors at z~1 the recently proposed scaling of the star formation efficiency with gas mass surface density.

About half of the stars in our Galaxy are born in binary systems meaning that their evolution might be affected by the presence of a companion. Many aspects of binary interaction are still unknown so understanding the products that result from interacting systems is crucial to unravel the physical mechanisms involved. A prototypical example of such post-interaction binary systems in the low- and intermediate-mass regime are Barium (Ba) stars. Ba stars are main-sequence or giant stars which show an enhancement of chemical elements that should not yet be overabundant at these evolutionary stages. Currently, it is widely accepted that these chemicals were transferred from a more evolved companion during a phase of mass transfer and that this companion evolved into a cool white dwarf. Understanding the orbital properties of these systems, as well as the stellar properties of the Ba star and its polluter, is the key to the system’s interaction history.

In the last years, the synergy between Gaia data, of unprecedented quality, high-resolution spectroscopy, long-term radial-velocity monitoring programmes, and state-of-the-art stellar and binary evolution models has contributed to a better understanding of the properties of Ba stars and provided new observational constraints to theoretical studies. The new Hertzsprung-Russell diagrams of Ba stars allowed us to accurately determine their evolutionary status and their masses. Additionally, we have recently determined the orbital properties of many main-sequence Ba stars, much less studied until now than their giant counterparts, which led to a thorough comparison of the properties of the two samples. The comparison between the distributions of masses, periods and eccentricities that resulted from this analysis allowed us to investigate the evolution of Ba-star systems between these two phases. Our models show that a second stage of binary interaction, this time between the main-sequence Ba star and its white-dwarf companion, also takes place in some systems, affecting the distribution of orbits observed among Ba giants.

The last thirty years of cosmochemistry and planetary science have shown that one major Solar System reservoir is vastly undersampled in the available suite of extra-terrestrial materials, namely small bodies that formed in the outer Solar System (>10AU). Because various dynamical evolutionary processes have modified their initial orbits (e.g., giant planet migration, resonances), these objects can be found today across the entire Solar System as P/D near Earth and main-belt asteroids, Jupiter and Neptune Trojans, comets, Centaurs, and small (diameter <200km) trans-Neptunian objects. This reservoir is of tremendous interest, as it is recognized as the least processed since the dawn of the Solar System and thus the closest to the starting materials from which the Solar System formed. Some of the next major breakthroughs in planetary science will come from studying outer Solar System samples (volatiles and refractory constituents) in the laboratory. Yet, this can only be achieved by an L-class mission that directly collects and returns to Earth materials from this reservoir. It is thus not surprising that two white papers advocating a sample return mission of a primitive Solar System small body (ideally a comet) were submitted to ESA in response to its call for ideas for future L-class missions in the 2035-2050 time frame. I will present an overview of the ideas listed in one of these two white papers and discuss how such a mission would be complementary to current and future ground based observations of primitive Solar System small bodies.
 

The evolution of a galaxy is a matter of synergy among diverse physical processes: some of them account for galaxy growth, while others regulate this growth. Since the interstellar medium (ISM) is the primary “repository” of galaxies, the study of its properties (e.g. density, extinction, ionization, metallicity) in different galaxy types and in different conditions within a galaxy through the use of integral field spectroscopy is fundamental to explore the different processes that affect its conditions and to assess their impact on the evolution of their hosts.

In the first part of this talk, I will discuss the results from the Measuring AGN under MUSE microscope (MAGNUM) survey. This survey comprises 9 local Seyfert galaxies, observed with the optical integral field spectrograph MUSE at the VLT, and characterised by extended outflows traced by the ionised gas. Specifically, we developed a novel approach based on the gas kinematics to disentangle high velocity gas in the outflow from gas in the disc. This allowed to spatially track the differences in the ISM properties of the two components, revealing the presence of an ionisation structure within the extended outflows that can be interpreted with different photoionisation and shock conditions, and tracing tentative evidence of positive feedback in a galaxy of the sample.

Finally, I will present a project focused on studying sistematically the impact of the ionisation parameter (i.e. a measure of the ionising photons with respect to the gas density) variations within galaxies on the measurement of metal abundances in the gas phase, using a sample of ~1800 star forming galaxies from the integral field unit Mapping Nearby Galaxies at APO (MaNGA) survey. I will show you how the still poorly understood ionization parameter is related with metallicity and other properties of galaxies (e.g. stellar mass), to what extent the inclusion of the [SIII]λλ9069,9532 lines can help to determine metallicity and ionization parameter, and how different photoionization models can relate with the observed line ratios.

We aim to test a key prediction of the theory of core accretion planet formation: that giant planets should be an order of magnitude rarer around low-mass (M dwarf) stars than around solar-mass stars. To do this we use a unique combination of HATSouth, GAIA, TESS, and ESO's new ESPRESSO spectrograph on the VLT.  Our aim is to discover transiting giant planets around M-dwarfs in the southern skies. I will highlight the discoveries that we have already made with this program, in particular focusing on our use of ESPRESSO/VLT.  I will then outline our plans to expand this survey using the full-frame image data from the TESS all-sky photometric survey.

Redbacks and black widows are binary star systems which host millisecond pulsar primaries. These spider systems are considered extremely important in understanding neutron star evolution as the second fastest rotating neutron star (PSR J0952-0607) and possibly one of most massive neutron stars (PSR J2215+5135) are a black widow and a redback respectively. Determining neutron star masses in spider systems relies on precise radio timing, optical photometry, and optical spectroscopy in order to determine the binary system parameters. In particular, the optical light curves of black widows indicate large temperature variations on the companions surface, which is often modeled as direct heating of the companions surface by the pulsar. This picture has been challenged in recent years, and in this talk I will discuss how these results may be affecting neutron star mass measurements.

High-contrast imaging techniques are rapidly evolving in the current years, thanks to the huge advancements in adaptive optics combined with coronagraphic observational strategies. 
In this talk, I will present some results obtained within the SHINE survey with SPHERE; moreover
I will introduce SHARK: a new facility that combining extreme adaptive optics with coronagraphy, dual-band imaging, and long-slit coronagraphic spectroscopy will be operating at LBT by the end of this year (2020). Very interesting, the two channels [SHARK+VIS and SHARK-NIR] will allow for the first time simultaneous observations from the B to the H bands: this is not currently available for any other instrumentation of this kind.
In the exoplanet framework, we aim at revealing (and characterising) relatively massive exoplanets at few tenths of arcsecond separations and contrasts around a few 10^-6.

The first direct detection of gravitational waves has confirmed the existence of binary black holes and opens a new window on the study of binary compact objects. In this talk, I will discuss the main astrophysical formation channels of binary compact objects in light of LIGO-Virgo data. On the one hand, models of stellar evolution and pair instability supernovae suggest a gap in the mass spectrum of black holes between ~60 and ~120 Msun. The boundaries of this gap depend on stellar rotation and on the efficiency of envelope removal. On the other hand, extreme dynamical processes in dense star clusters can fill the mass gap, via multiple stellar collisions and dynamical exchanges. Moreover, stellar dynamics enhances the formation of black hole - neutron star systems with extreme (<1:10) mass ratios. Based on a data-driven model, I will discuss the merger history of dynamical versus isolated binary compact objects across cosmic time, and its dependence on the cosmic star formation rate and on the stellar metallicity. Finally, I will show that the merger rate per galaxy mostly depends on the total stellar mass and on the star formation rate.

Planetary nebulae are some of the most strikingly beautiful astrophysical phenomena known, gracing many a glossy-paged, coffee-table book and earning them the nickname "cosmic butterflies". While classical stellar evolutionary theory states that all intermediate mass stars should produce a planetary nebula, forming as the star leaves the Asymptotic Giant Branch and evolves towards the white dwarf phase, it is now clear that a significant fraction of planetary nebulae originate from a binary evolutionary pathway. As the immediate products of the common envelope, close-binary central stars of planetary nebulae offer a unique tool with which to study this rather poorly understood phase of binary evolution. Furthermore, as the nebula itself represents the ionised remnant of the ejected common-envelope, such planetary nebulae can be used to directly probe the mass, morphology and dynamics of the ejecta. Here, I will summarise our current understanding of the importance of binarity in the formation of planetary nebulae as well as what they can tell us about the common envelope phase - including the possible relationships with other post-common-envelope phenomena like novae and type Ia supernovae.

The large-scale structure (LSS) of the universe is made by a network of groups and clusters of galaxies, extended filaments and voids (e.g. Peebles, 1980). According to the Lambda-Cold Dark Matter (LCDM) galaxy formation theory, the clusters of galaxies in the LSS are expected to grow over time by accreting smaller groups along filaments, driven by the effect of gravity generated by the total matter content (e.g. Bond & Szalay 1983).

In the deep potential well at the cluster centre, the galaxies continue to undergo active mass assembly and, in this process, gravitational interactions and merging between systems of comparable mass and/or smaller objects play a fundamental role in defining the galaxies' morphology and the build-up of the stellar halos. This is an extended (≥ 100 kpc) and faint (μg ≥ 26 - 27 mag/arcsec^2) component made of stars stripped from satellite galaxies, in the form of streams and tidal tails, with multiple stellar components and complex kinematics (see Duc 2017, Mihos 2017 as reviews). During the infall of groups of galaxies to form the cluster, the material stripped from the galaxy outskirts builds up the intra-cluster light, ICL (De Lucia & Blaizot 2007; Puchwein  et al. 2010; Cui et al. 2014). This is a diffuse and very faint component (μg ≥ 28 mag/arcsec^2) that grows over time with the mass assembly of the cluster, to which the relics of the interactions between galaxies (stellar streams and tidal tails) also contribute. 

In this framework, exploring the low surface brightness (LSB) universe is a crucial ingredient to map the mass assembly of galaxies at all scales (from galaxies to clusters) and in all environments (in the low-density groups of galaxies as well as in rich clusters), to constrain their formation within the LCDM paradigm. 

In this talk, I will focus on the low-density environments as group of galaxies and on the main results obtained by exploring them at the LSB regime, by using deep imaging data from the VEGAS survey.

We observe a homogeneous sample of 72 solar-mass members of the approximately 16 Myr-old Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association (Sco-Cen). We obtained two minutes total integration for each of the 72 targets using VLT/SPHERE/IRDIS. We construct a reference library of point spread functions from all the observed target stars and apply principal component analysis to remove the effects of the stellar halo. Despite the very short integration time, we are able to detect 10 Jupiter-mass objects at separations of 0.2 arcseconds and in the background limited regime we are sensitive to companions with masses as low as 3 Jupiter masses.

The first epoch observations already reveal a shadowed transition disk around Wray 15-788 that shows signs of ongoing planet formation. Second epoch observations of only five systems confirm two sub-stellar companions at wide separations (>150au) by common proper motion analysis. Comparison to evolutionary models of sub-stellar objects provides preliminary estimates of approximately 14 and 30 Jupiter masses.

With additional follow-up observations of the remaining 49 systems that host low-mass companion candidates, our survey will finally provide a complete census of wide orbit sub-stellar companions to a statistically highly significant sample of young, solar-type stars.

In this talk, I will present an extremely cold, planetary-mass brown dwarf which bridges the temperature gap between the known brown dwarf population and the coldest brown dwarf ever discovered. W0830 was identified through the Backyard Worlds: Planet 9 citizen science collaboration, which brings together over 150,000 people around the world in identifying cold, fast-moving sources through a series of WISE images. W0830 is a red, fast-moving source with a faint W2 detection and an upper limit in W1 photometry in multi-epoch AllWISE images. We have characterized this object with Hubble and Spitzer Space Telescope follow-up photometry. The available evidence points to a Y1 source at Teff ~ 350 K with a planetary mass of 4-13Mjup, as extrapolated from the known Y dwarf population. This object joins a small, yet growing sample of “missing link” objects connecting brown dwarfs to giant planets in terms of temperature.

Local Seyfert galaxies are the perfect laboratories to study whether and to what extent the emission from the Active Galactic Nuclei (AGN) affects the properties of the host-galaxy interstellar medium (ISM). This can be achieved through a multi-wavelength strategy, which allows us to fully characterise the sources in terms of AGN activity and host-galaxy properties (e.g., star formation rate, galaxy stellar mass, different gas phases).

In this work, we focused our attention on a sample of mid-IR selected Seyfert galaxies in the local Universe, which benefits from an extensive data coverage. In particular, we performed a systematic study of their nuclear activity through broad-band X-ray spectral analysis, necessary to unveil the intrinsic AGN luminosity and the level of obscuration. Exploiting mm observations (from ALMA and APEX), we characterised the host-galaxies in terms of the molecular gas component.

A galaxy's cold gas reservoir determines the rate at which it can be forming stars, therefore measuring the cosmic evolution of the cold gas mass of galaxies is critical to our understanding of galaxy evolution. Obtaining such measurements for large samples of galaxies is still challenging even in the ALMA era. Earlier studies of the cosmic gas evolution explored up to about z~3 and show significant discrepancies. As the (sub-)millimeter dust continuum has now been established as reliable tracer by several studies, we have conducted an effort to exploit the public ALMA archive data in the COSMOS deep field, in a coherent, systematic way to quantify systematic biases in using dust continuum to infer cold gas mass and determining cosmic gas evolution. Our project A³COSMOS recently published ~2000 ALMA images covering ~230 sq. arcmin with over 1500 high-confidence (spurious fraction <10%) ALMA detections based on our characterized statistics. These result in a robust galaxy catalog of ~700 galaxies, and newly constrained empirical gas fraction and depletion time evolution function published with our papers. Finally, I will present our derived cosmic cold gas evolution out to z~6, and detail the implications for galaxy evolution and cosmological simulations. 

A fundamental question in galaxy evolution is how galaxies acquire diverse colours and morphologies. The current paradigm suggests that massive galaxies experienced accelerated growth in the early Universe and eventually quench their star formation. Exactly how galaxies quench is not well-understood. Many mechanisms have been proposed in the literature, yet a definite conclusion remains elusive. I will present an overview of the current state of the art and discuss future perspectives on solving this decade-old puzzle.

As machine learning codes are becoming ubiquitous in the literature, some skepticism remains because of the "black box" nature of most of these algorithms, inextricable biases in their training sample, and other limitations. Sharing these concerns, we tested unsupervised "manifold learning" algorithms with a realistic mock galaxy catalog (up to z=4) derived from cosmological hydro-dynamical simulations. I will present the results obtained by analyzing this data with "self-organizing maps", and discuss future, groundbreaking applications in understanding galaxy evolution.

Cl J1449+0856 is an excellent case to study the development of environmental trends seen at low redshift - a galaxy cluster at z=2 that already shows evidence of a virialised atmosphere. We have obtained a wide range of observations of cluster members, including multiple transitions of CO and the dust continuum emission. With these data, we study properties such as molecular gas excitation, star-formation efficiency and gas fraction, to reveal how obscured star-formation, ISM content and AGN activity are linked to environment during this crucial phase of mass assembly. Probing beyond the massive population, we finish by comparing low-metallicity ISM scaling relations at z=2 with those calibrated in the local Universe, investigating this so-far poorly probed ISM regime.