Seminars and Colloquia at ESO Garching and on the campus

Planets born in circumstellar disks create various disk substructures, such as gaps, rings, spirals, vortices. Similar structures are observed widely with ALMA, SPHERE and similar instruments. At least some of these disk features are likely due to forming planets, however there are also other mechanisms to explain them. Planets also create various motions inside the protoplanetary disks, e.g. the meridional circulation that was recently observed with ALMA.

Carrying out high resolution, 3D dust+gas hydrodynamic simulations with radiative transfer already included, allow us to create realistic “mock observations” or “synthetic images” for a given instrument & telescope combination. These mock observations can be compared with already existing real data, or prepare for future observational proposals. We use them to understand how massive forming planets could be observed with the different instruments, how the planet-disk interactions look like on various wavelengths and what planet-generated features we can observe with the current & near-future instrumentation. Furthermore, since the 3D hydrodynamic simulations exactly inform us about the dust- and gas disk mass, we can use the mock observations to determine how much we underestimate the real disk masses due to assuming an optically thin disk.

The albedo of a celestial body is the fraction of incident starlight reflected by it. The study of the albedos of Solar System objects is at least a century old, at least in the Western world. As examples: Bond (1861) speculated on the near-unity albedo of Jupiter, while Russell (1916) observed the opposition surge of the Moon near and at full phase. The light of a planet or moon varying with orbital phase is known as its phase curve. Modern astronomical facilities have enabled the measurement of phase curves of reflected light and thermal emission from exoplanets (e.g. Kepler, TESS, CHEOPS, Hubble, Spitzer), which enables the investigation of atmospheric dynamics and aerosols. In the current talk, I will concisely review and discuss historically important work, including seminal contributions by Seeliger (1888), Chandrasekhar (1960), Sobolev (1975) and Hapke (1981). These introductions set the stage for a detailed discussion of our recent work on generalising these classic works to derive closed-form, ab initio solutions for the geometric albedo and reflected light phase curve. This novel theoretical framework is applied to Kepler space telescope data of the hot Jupiter Kepler-7b, where we demonstrate that one may infer fundamental aerosol (single-scattering albedo, scattering asymmetry factor) and atmospheric (geometric albedo, Bond albedo, phase integral) properties from precise photometry alone, thus providing powerful complementary information to spectra. Another case study are the Cassini phase curves of Jupiter, which were measured in the early 2000s by the Cassini space mission but never subjected to Bayesian inference.By inverting the Cassini phase curves, we infer that aerosols in the Jovian atmosphere are large, irregular, polydisperse particles that may be responsible for causing coherent backscattering of sunlight.

Deep Investigation of Neutral Gas Origins (DINGO) is a deep blind survey of atomic hydrogen (HI) using the Australian SKA Pathfinder (ASKAP). Its aim is to study the evolution of HI from the current epoch to a time when the Universe was two-thirds is present age (z ∼ 0.4), through HI 21 cm emission spectral line observations of the Galaxy And Mass Assembly (GAMA) survey regions. The survey employs a two-tiered strategy: starting with z ≤ 0.1 and then extending to 0.25 ≤ z ≤ 0.4. Most of the science for DINGO will be done using stacked detections of the HI emission, though it will also yield unprecedented numbers of direct detections. We are already midway though the DINGO Pilot survey. I will discuss the present status of the DINGO Pilot survey and the initial data and associated science coming out of it. I will particularly focus on a study of the gas content of galaxy groups and pairs as compared to isolated galaxies, done using a combination of archival ALFALFA and DINGO Pilot data. We are finding possible evidence for the presence of large amounts of inter-galactic gas in low mass galaxy groups.

The clustered nature of star formation leaves a long-term imprint on galaxies, stars, and planets. At young ages, stellar clustering subdivides galaxies into individual building blocks undergoing vigorous, feedback-driven life cycles that vary with the galactic environment. These units structure the interstellar medium spatially, dynamically and chemically, and collectively define how galaxies form stars. At old ages, the relics of clustered star formation persist as ancient globular clusters, which hold a wealth of information allowing us to reconstruct the assembly histories of galaxies, culminating in the reconstruction of the Milky Way’s merger tree. Towards smaller scales, stellar clustering has a measurable impact on the evolution of protoplanetary discs, the architectures of planetary systems, and the properties of planets themselves. I will discuss how this web of physical processes across a hierarchy of scales defines the cosmic ecosystem that we live in, and demonstrate that stellar clustering is at its focal point.

It was back in 1979 that I began a series of time-resolved optical observations of the X-ray burst source 4U 1636-536 (aka MXB 1636-53 and V801 Ara), resulting in the detection of several bursts in common with X-ray satellites.

Perhaps for reason of technical difficulties, there have been few attempts to improve on these results. During the talk, I shall go over the scientific case, and suggest ways ahead.

The demographics of exoplanets show that planet formation has to be a very efficient process, capable of forming planetary systems in a wide range of environments. One puzzling observation is the high occurrence of transiting planets around low-mass M dwarfs, where a reduced planet formation efficiency would be expected based on low protoplanetary disk masses. In this talk I will paint a consistent picture of exoplanet populations --- mainly consisting of hot sub-Neptunes and cold giant planets --- that is constrained by transit, radial velocity, direct imaging, and micro-lensing surveys, and that is also compatible with observed protoplanetary disk structures. To solve the M dwarf riddle, I will present a pebble accretion model where giant planet cores forming outside the snow line block the drift of pebbles into the inner disk, suppressing the formation of rocky planets there. This leads to a decreased occurrence rate of super-earths and mini-Neptunes around sun-like stars that is consistent with the observed stellar mass dependence in the Kepler planet occurrence rates of F,G,K and M stars.

The Galactic disk exhibits complex chemical and dynamical substructure thought to be induced by the bar, spiral arms, and satellites. Here, we explore the chemical signatures of bar resonances in action and velocity space and characterize the differences between the signatures of corotation and higher-order resonances using test particle simulations. Thanks to recent surveys, we now have large homogeneous datasets containing metallicities and kinematics of stars outside the solar neighborhood. We compare the simulations to the observational data from Gaia EDR3, LAMOST DR5, and APOGEE DR16 and find weak evidence for a slow bar that associates the ``hat'' moving group with its outer Lindblad resonance and ``Hercules'' with corotation. While constraints from current data are limited by their spatial footprint, stars closer in azimuth than the Sun to the bar's minor axis show much stronger signatures of the bar's outer Lindblad and corotation resonances in test particle simulations. Future datasets with greater azimuthal coverage, including the final Gaia​​ data release, will allow reliable chemodynamical identification of bar resonances.

Li is the element with the largest number of known astrophysical nucleosynthetic processes, but also with several astronomical puzzles. It is  a primordial element produced in the first 3 minutes, but   Li abundance in the old halo population of the Galaxy  is lower by a factor 3 than predicted by Big Bang models when the baryonic density is  either from the CMB or from primordial deuterium.  Also,  the same abundance is seen in metal poor Gaia-Enceladus candidate stars, which are  effectively extragalactic. This disagreement   is known as the Cosmological Lithium problem for which  a satisfactory solution is still to be found. A possible fix by pre-main sequence stellar depletion will be   discussed briefly as an example. Spallation processes in the interstellar medium    also produce Li, but  not enough  to reach the  abundance observed  today, and one or more stellar sources are required  to make most (~ 70%) of the Li in the Galaxy.  Several candidates have been proposed but  none is really satisfactory. Novae were  suggested in the early 70’s but only recently  Be-7, the Li  parent nuclei,  has been detected in novae outburst. Ongoing observations of Be-7 in few recent novae will be reported,   including the first detection of Be-7 in two novae in the Small Magellanic Cloud.   The   Be-7(= Li-7) yields obtained from novae are very high,  higher than model predictions, which represents a matter of concern. Taken at face value the observed   yields overproduce the present meteoritic Li abundance by  four orders of magnitude, and  therefore novae look as  the most promising candidates for "THE" source of Galactic  Li. This is also supported by detailed  chemical evolution models  of  Li evolution in the thick and thin disks of the Galaxy.

"The bigger picture of dwarf galaxy alignments in the Local Group and beyond", Marcel Pawlowski (Leibniz Institut fur Astrophysik)

Abstract: The satellite galaxy systems of several well-studied galaxies, in particular the Milky Way and Andromeda, have been found to show signs of correlated Planes of Satellites. These structures might be related on even larger scales. Two surprisingly symmetric planar arrangements can be identified among the more isolated dwarf galaxies in the Local Group, and satellite planes appear to show some alignment with the larger-scale cosmic web around their hosts. I will provide a brief overview of the observed satellite and non-satellite planes in relation to each other, to the Local Group dynamics, possible backsplash galaxies, and the larger-scale cosmic web, all of which might hold clues to understand the origin of these structures.

and

"Solving the problem of disks of satellites with modified gravity", Michal Bilek (LERMA)

Abstract: Simulations in standard cosmology leave only a small chance for disks of satellites being comprised of primordial galaxies. The observed distribution of satellites would be more natural if the satellites were tidal dwarf galaxies, that is small galaxies that form by gravitational collapse in tidal arms of interacting galaxies. If so, then the observed internal dynamics of the satellites indicates that gravity is not Newtonian. We run a simulation of the history of the Local Group in the leading alternative, the MOND modified gravity theory. The simulation was tuned only to reproduce the observed relative distance, velocities and disk orientations of the Milky Way and Andromeda galaxies. It showed that the two galaxies had a close fly-by 6.8 Gyr ago that produced long tidal arms. The remnants of the arms resemble the observed disks of satellites. The simulated Milky Way developed a warp resembling the observed one.

The dispersing element is one of the key optical element in modern spectrographs for astronomical application. Indeed, it defines the dispersion, resolution of the spectrograph. Moreover, it is one of the less efficient component in the instrumentation; therefore, it is crucial to have a dispersing element with high diffraction efficiency in the target spectral range.

In this framework, Volume Phase Holographic Gratings (VPHGs) have become the reference technology in the last 15 years especially for low and medium resolution spectrographs in the 0.3 – 2.5 mm spectral range thanks to their very high efficiency (more than 90%), large dispersion and size, easy customization. Moreover, they have been used as cross-disperser in echelle high-resolution spectrographs such as ESPRESSO@VLT. For these reasons, they are mounted on spectrographs such as MUSE and FORS2 @ VLT, HERMES @ AAT, WEAVE@WHT etc. In the near future, MOONS@VLT, 4MOST@VISTA will be (partially) equipped with such gratings, as well as MOS spectrographs for the ELT.

More recently, other technologies has entered the scene of astronomical spectrographs. In particular binary gratings have shown to be efficient especially when high dispersions and large sizes are required and they can be manufactured exploiting lithography and holography. Moreover, new configurations of dispersing elements have been proposed to improve the resolution/spectral range and to cover the detector array in an efficient way.

In this talk, the actual status of the VPH technology is discussed considering the capabilities developed at the National Institute of Astrophysics (INAF) in Italy; the lesson learnt working in the field of dispersing elements is presented together with some considerations in the choice of the dispersing element.

We show results form state-of-the-art gas modelling within three-dimensional numerical simulations including time-dependent non-equilibrium atomic and molecular chemistry coupled to different UV backgrounds, as suggested by recent literature, and various physical processes taking place in cosmic gas during structure formation (gas self-shielding, dust grain catalysis, metal fine-structure cooling, photoelectric and cosmic-ray heating). We predict neutral-gas (ΩHI) and H2 (ΩH2) density evolution, as well as depletion times in light of the latest ALMA, VLA, NOEMA, UKIDSS observations up to redshift z~7 and discuss their main drivers over cosmological epochs. Our findings suggest that non-equilibrium molecular cooling is efficient at lowering cold-gas temperatures in a wide variety of environments and since the first half Gyr. Different physical processes can affect H2 evolution in a non-trivial way and, thus, in addition to HI, H2 data appear to be pivotal probes for assessing cold-gas abundances and the role of UV radiation.

Galaxies are known to occupy preferential regions in the star formation versus stellar mass (SFR-M*) plane. More than a decade ago, the existence of two main regimes have been recognised: a so-called main sequence (MS) for star-forming galaxies and a passive cloud for galaxies with negligible instantaneous star formation rates. Since then, the MS has been considered the general rule for galaxy growth from low to high redshifts. Until recently, there was scarce evidence for the presence of starbursts, i.e. galaxies with a star formation activity that is significantly elevated with respect to the MS.
In this talk I will revisit the importance of starburst galaxies in the light of the most recent results in this field. I will argue that there is a clear starburst/MS bimodality for the modes of galaxy star formation, which becomes evident at high redshifts (z>2-3), when the starburst mode dominates the total SFR budget. Interestingly, state-of-the-art galaxy formation models fail to predict the starburst population overall, suggesting that the physics behind the starburst mode may be absent in these models.

Thick disks are ubiquitous in nearby spiral galaxies, and many mechanisms, including mergers, have been proposed to explain their formation. I will first use a suite of zoom cosmological simulations to explore the connection between a galaxy's formation history and the structure of its disc. I will discuss some results on the structure of the Milky Way's thick disc, and what we can infer about the formation history of our Galaxy. Finally, I will present MUSE observations of NGC 5746, a massive (~10^11 Msun) edge-on disc galaxy. We find that a massive and extended disc formed very early: 80 per cent of the galaxy's stellar mass formed more than 10 Gyr ago. Most of the thick disc formed during that early phase. Later on, around ~8 Gyr ago, a ~1:10 merger happened. The satellite did not cause significant vertical heating (and also did not contribute to the growth of a classical bulge). It was however an important event for the galaxy: by depositing its stars throughout the whole galaxy it contributed ~30 per cent of accreted stars to the thick disc. This work highlights the complexity of thick discs, and the need for further observations to probe the build-up of discs across a wide range of masses.

The feedback - how young high‑mass stars heat, stir, and push on their surrounding gas - from young stars (i.e. pre-supernova) is thought to play a crucial role in galaxy evolution; via e.g. molecular cloud destruction, driving large gas dynamics such as outflows and facilitating supermassive black hole feeding and AGN activity, affecting the formation of planetary systems, and (e.g. pre‑biotic) chemical evolution. The key missing piece in our understanding of feedback is to constrain the varying effects of stellar feedback as a function of its host environment, which is fundamentally important for our understanding of how young stellar feedback varies across galaxies, between galaxies, and, crucially, how this currently differs from the high‑z universe. In this talk, I will present a recent analysis of the various feedback mechanisms acting within a sample of several 1000 HII regions identified from the PHANGS-MUSE survey of nearby star-forming, main sequence spiral galaxies. These optical spectroscopic maps are essential to constrain the physical properties of the HII regions, which we use to investigate their internal pressure terms to gain a first look at the dominant feedback mechanisms as a function of the external environment (provided by PHANGS-ALMA). I will then end this talk by outlining an ambitious new follow-up project that utilises HST and JWST observations to 1) resolve these HII regions and 2) identify their sources of ionisation, which will provide a complete end-to-end picture of young stellar feedback for a large sample of HII regions.

The next generation of astronomical observatories bring a realistic prospect of paradigm-shifting constraints on the nature of dark matter and dark energy, both through deeper observations of large scale structure and by pushing to fainter surface brightness galaxies. I will discuss the unique computational challenges that producing simulations for this era pose. On the one hand we wish to simulate large volumes to gain representative samples of galaxies and to understand the cosmological implications of forthcoming survey data from e.g. LSST. On the other, we also want to maintain very high resolution to resolve highly non-linear astrophysical processes and internal kinematics for Gaia, MaNGA and the like. These two requirements result in a tension on how to best spend limited computer time. I will argue that a new approach to simulations, in which we use statistical models to tailor cosmological initial conditions for different questions, can help relieve this tension. I will mainly focus on recent applications to understanding the diversity of dwarf galaxies, and will also give a quicker overview of results for higher mass galaxies and large scale structure.

"Dynamical Friction in Barred Spiral Galaxies", Francesca Fragkoudi (ESO)

Abstract: The formation and properties of stellar bars in spiral galaxies are both tightly linked to the properties of their dark matter halos. For example, it has been shown that dynamical friction induced by a massive dark matter halo will slow down the rotation speed of bars. While numerous observational studies have found that bars tend to rotate fast, numerical simulations within the LCDM framework tend to find that bars slow down excessively. This has given rise to an apparent tension between fast bars and the LCDM cosmological paradigm, which has been highlighted over the past years in the literature. I will present recent findings from cosmological simulations that help to shed light on this longstanding issue, and discuss this within the context of recent claims in the literature of a > 10sigma tension between fast bars and LCDM.

and

"Cosmological Voids", Eelco van Kampen (ESO)

Abstract: A large local under-density (void) would provide the simplest explanation for the mismatch between local determinations of the Hubble constant and those derived from cosmological probes, which results in smaller estimates than the local ones. Such a large local void acts like an under-dense mini-Universe with a correspondingly higher Hubble constant (a 'Hubble bubble'). There is some observational evidence for this, but the question is whether the claimed local void is large and/or empty enough to remove the Hubble tension between local and cosmological estimates.

The thermal Sunyaev-Zeldovich (tSZ) effect is a powerful, roughly redshift independent tool for discovering clusters of galaxies. The mass function of these clusters is a sensitive probe of cosmology, particularly sigma_8. However, accurate parameter estimation from this mass function requires accurate, unbiased mass estimates for the clusters, as well as a thorough understanding of the selection function of the underlying cluster catalog. In particular, radio and dusty galaxies which are spatially correlated with clusters may bias tSZ mass estimates. Similarly, astrophysical processes and structures, including shocks and jets, can cause significant deviation of the actual cluster profile from the assumed cluster profile, biasing mass reconstruction. In this talk I will discuss a recent work wherein we calibrated the mass-richness relation for an IR selected, high redshift cluster catalog using tSZ derived masses from the Atacama Cosmology Telescope (ACT), a Cosmic Microwave Background survey instrument. I will in particular detail the efforts we made to de-bias the mass estimates from point source effects. Finally, I will cover ongoing efforts to detect AGN supported X-ray cavities in the cluster MS0735 using the high resolution, 90GHz MUSTANG-2 instrument on the Green Bank Telescope (GBT). In addition to helping us de-bias mass estimates, a tSZ measurement of the bubble in MS0735 would shed light on the support mechanism for that bubble, and hence on astrophysical feedback processes that counteract radiative cooling of the intercluster medium.

Our understanding of the motions of stars within our Milky Way and of the many small galaxies that orbit around it has changed dramatically over the past few years owing to new observational surveys and significant advancements in our understanding of galaxy structure. New surveys now enable us to precisely measure the motions of objects that orbit our Galaxy, like clusters of stars, satellite galaxies and stellar streams. The motions of these objects trace the so-called “dark matter” distribution, the unseen material that is expected to exist within and around our Galaxy, making up the bulk of its mass. However, connecting these data to theoretical models requires understanding the influence of the Milky Way’s largest satellite galaxy, the Large Magellanic Cloud (LMC). I will provide an overview of this evolving picture and how we can test the cold dark matter paradigm in the near future using next-generation surveys and simulations that include the LMC.

I will continue the discussion started on Friday 29/10 at coffee regarding the preprint by J. Kormendy (https://arxiv.org/abs/2110.14115v1) who aims at calibrating citations count metrics against the evaluation of the researcher's research impact by senior astronomers, with the goal of building "prediction machines". In a short presentation, I will introduce the methodology and main arguments of the paper and argue that this is not a very useful study, and that in my opinion its results should not be used.

Galactic Archaeology is commonly referred to the studies of Galactic history using chemical abundances of long-lived stars as fossil records. Today, thanks to Gaia and the large spectroscopic surveys available to the community, this field of study is going through a revolution, as we now have information on about 20 different chemical elements, ages and kinematics for thousands of stars. However, putting this huge multidimensional information together is everything but straightforward. I will introduce a new method that takes advantage of this multidimensional information by literally using long-lived stars as fossil records and putting these into phylogenetic trees, like a biologist.

The effect of strong dynamical perturbations on the planet formation process is uncertain.  In particular, a close-by companion star is expected to stir up planetesimals in the protoplanetary disk, leading to high-speed destructive collisions.  Simple estimates based on the parameters of known planet-hosting binary systems suggest that km/s collision velocities are not unreasonable.  These are sufficient to destroy planetesimals 100’s of km in size.  I will describe work in which we accurately calculated planetesimal collision speeds and rates, and then used these to run a coagulation-fragmentation simulation to model their growth or destruction.  We find that for reasonable disk parameters, planetesimal coagulation is possible starting from bodies of a few to a few tens of km. This necessary starting planetesimal size is smaller than that found in previous work, suggesting that planet formation via core accretion is likely viable in these systems.

The archaeological record of the Milky Way is being unveiled through measurements of its stars. This is an endeavour across a huge range of scale, where both individual stellar atmospheres and million star surveys are revealing the connection of present to past. I will present my recent work that makes measurements of stellar ages, and uses these ages as the fundamental variable to learn the formation and evolutionary properties of the Galaxy: where stars were born, how they have moved over time, and how individual abundances can quantify the diversity of the environment in which they formed. The overarching goal of this ensemble of studies is to link the chemical to the structural evolution of the Milky Way, showing relationships that directly enable comparisons to other galaxies.

The star-formation rate density (SFRD) and metal density (ZD) of the Universe are key diagnostics for understanding galaxies, as they encode the relative significance of all the main astrophysical processes driving galaxy evolution.

In this talk, I will present new results on the evolution of the SFRD and ZD from z=7 to 0 from the TNG100, EAGLE, and L-GALAXIES 2020 cosmological simulations. I will show that, while these simulations are able to reproduce either the observed SFRD or ZD, none is able to simultaneously match both. For example, some simulations can reproduce the high metal content observed in the neutral gas of damped Lyman-alpha (DLA) systems at z~3-5 (e.g. Peroux & Howk 2020), but require cosmic star formation rates in excess of those currently observed from FUV data (e.g. Madau & Dickinson 2014) to do so.

I will discuss three scenarios in which observations and simulations could be resolved: A) the cosmic SFRD at high redshift is higher than that inferred from FUV-FIR data, in which case TNG100 could be correct. B) the mean mass of DLA host galaxies is higher than that of the underlying galaxy population, in which case L-GALAXIES 2020 could be correct. C) neither of the above are true, in which case EAGLE could be correct, although at the expense of over-estimating DLA metallicities. These results demonstrate the huge importance of considering the ZD alongside the SFRD when constraining galaxy evolution models.

The formation of stars and planetary systems is a complex phenomenon that relies on the interplay of multiple physical processes, and is expected to occur in cold and dense filamentary structures forming within the so-called molecular clouds. In these regions, molecular hydrogen can exist in two spin states, ortho and para, with the ratio between them having a significant impact on the abundance of other molecules, in particular deuterated ones. While a general agreement exists on the typical average properties of these filaments, the chemical conditions at the onset of gravitational collapse are still poorly constrained, with theoretical models often exploring a large parameter space. I will show, via self-consistent magnetohydrodynamic simulations, that the ortho-to-para ratio is already very low in proto-filaments with densities around 10^3-4 cm^-3, much lower that the typically assumed value, and that a high cosmic ray ionisation rate is needed to reproduce observed diffuse clouds. I will finally discuss the impact of these two results on the deuteration process, and on the use of chemical clocks based on deuterated species.

In this talk, I will review the physics of accretion and outflows, focusing on the relativistic jets, as revealed by 3D general relativistic simulations of magnetized plasma near spinning black holes. I will discuss the conditions necessary for jet formation, what the jets can reveal about the central engine, and the effects the jets can have on their environment.

Nuclear star clusters (NSC), dense and compact stellar systems located at the bottom of the galactic potential well, are important tracers of the dynamical state of galaxies and their evolution. Stellar kinematics, which brings the footprint of the dynamical history of galactic structures, helps us to disentangle between the two main formation scenarios proposed for NSCs: star-cluster infall or in-situ star formation. We present parsec-scale kinematics of 11 nearby galactic nuclei, derived from adaptive-optics assisted integral field spectroscopy at (near-infrared) CO band-head wavelengths. We focus our analysis on the balance between ordered rotation and random motions, which can provide insights into the dominant formation mechanism of NSCs. We divide our target sample into late- and early-type galaxies, and discuss the nuclear kinematics of the two subsamples, aiming at probing any link between NSC formation and host galaxy evolution. The results suggest that the dominant formation mechanism of NSCs is indeed affected by the different evolutionary paths of their hosts across the Hubble sequence. More specifically, nuclear regions in late-type galaxies are on average more rotation dominated, and the formation of nuclear stellar structures is potentially linked to the presence of gas funneled to the center. Early-type galaxies, in contrast, tend to display more slowly rotating NSCs with lower ellipticity. However, some exceptions suggest that in specific cases, early-type hosts can form NSCs in a way similar to spirals.

The Atacama Large Millimeter Array (ALMA) has granted us the sharpest view of protoplanetary disks, the planet formation environment, to date. These disks, reservoirs of planet-forming material, have been found to host a stunning variety of substructure. Gaps, rings and spirals are routinely observed in the distribution of large dust grains, suggestive of dynamical processing by an unseen population of recently formed planets. I will demonstrate how through studies of the gas structure, in concert with the development of new data analysis techniques, we have been able to detect the young planets responsible for the structure we have seen in the dust. I will show how we are now able to conduct a thorough chemical inventory of the planet forming material, and trace the delivery of these materials to young planets during the accretion of their atmospheres. To conclude, I will high how the mapping of the dynamical structure of the disk is providing a unique opportunity to identify the hydrodynamical processes that are driving planet formation and influencing the global evolution of the protoplanetary disks.

In this talk I will tell you about the exciting ESA space science missions that we are currently working on with our science communications team: such as JWST, JUICE and Euclid. In the second half I will talk about storytelling. Storytelling is an important tool for communicating with the public and with your scientific community. Storytelling is not only useful to prepare for outreach talks or media interviews, but for example also for writing grant proposals or giving a (poster) presentation at a conference. During this talk I will share a few tips and tricks that can help you to define your story about your research or preferred topic in an engaging way.

Tracing the peaks of the matter distribution in the Universe, galaxy clusters can be used as powerful cosmological probes, as well as fantastic astrophysical laboratories, due to the complex interplay between their constituents. Presently, cluster cosmology is limited by systematic on the mass measurements, also linked to their detection. High mass systems at low and intermediate redshifts (z<~0.6) have been extensively characterized, partly because it is simply easier to obtain direct mass measurements for high signal to noise data.

In this talk, I will discuss the necessity to explore the low mass/high redshift regime to better exploit the samples coming from next generation surveys, and the opportunities given by multi-wavelength data combination approaches. I will present an observational project aiming at mapping three below mass clusters in SZ with the millimeter camera NIKA2, and the optical +X-ray+SZ characterization of the first target, appearing as a “bullet like cluster” at z~1. Finally, I will conclude on how to use information about individuals systems to inform cosmological analyses of large samples, via the use of simulations.

IceCube detects more than 100,000 neutrinos per year in the GeV to 10 PeV energy range. Among those, we have isolated a flux of high-energy neutrinos of cosmic origin, with an energy density in the extreme universe similar to that of high-energy photons and cosmic rays. We identified their first source: on September 22, 2017, following an IceCube neutrino alert, observations by other astronomical telescopes pinpointed a flaring active galaxy, powered by a supermassive black hole, as the source of a cosmic neutrino with an energy of 290 TeV. We will review recent progress in measuring the cosmic neutrino spectrum and in identifying its origin.

Following a dynamical encounter with Sgr A*, binaries in the Galactic Centre (GC) can be tidally separated and one member star ejected as a hyper-velocity star (HVS). As GC-born objects located in more observationally accessible regions of the sky, HVSs can provide insight into the stellar population(s) within the inner parsecs of the Milky Way. In this talk I will show that the absence of confident HVS candidates in the radial velocity catalogue of Gaia Data Release 2 offers constraints on still-uncertain properties of the GC environment, namely the shape of the stellar initial mass function in the GC and the ejection rate of HVSs. Forecasting ahead, I will illustrate how these constraints will improve if/when more HVS candidates are unearthed in future Gaia data releases.

S0 galaxies make up one of the largest population of galaxies in the Universe, yet how they form has remained an unresolved question. A number of formation pathways have been proposed and tested in idealised simulations, however which pathways (and their relative contribution) are actually occurring in a cosmological context remains an open question. Here we combine observations and simulations to argue that two main formation pathways are transforming spiral galaxies into S0s; galaxy mergers and gas stripping during cluster infalls. In the observational study, we use stellar kinematics to show that the range of rotational support in the S0 population is difficult to explain using a single formation pathway, suggesting multiple pathways are active. In a follow-up study using the IllustrisTNG simulation, we then traced the history of S0 galaxies and identified their formation mechanism. We found that 37 percent formed from spirals via mergers and 57 percent formed from the gas stripping of a spiral falling into a larger cluster environment, with the remainder forming due to gas exhaustion.

Discussion on gender equity and diversity plans of MPA, MPE and ESO, organised by the Women Encouragement Group. We will have a short talk from the equity officers about the plans of each institute, followed by an informal discussion over tea/coffee and snacks where we can share our thoughts. Everyone is encouraged to join the discussion (regardless of gender). The meeting will be hybrid so that one is free to join in person (up to maximum room capacity) or via Zoom.

Choosing where to apply, 30min talk

Components of an application, Talk tour, Timeline, Job interviews, Making decisions, 30min Q and A session

The Dark Energy Survey (DES) included a six-year, 5000 sq. deg. observing program using the Dark Energy Camera on the 4m Blanco telescope at CTIO. Observations are now complete, but this is just the start of shedding light on the fundamental mysteries of the Universe with DES. I’ll discuss the most recent analysis of weak gravitational lensing and large-scale structure measurements using the first three years of DES data. The power of this data set, which has produced calibrated shape measurements for over 100 million galaxies, has required the development of novel new approaches to calibrating shear and photometric redshift information. I will describe these advances and our measurements, and comment on what we can look forward to with future DES science.

MEET THE SPEAKER: Wednesday, October 6, at 2 p.m. @ MPA E.0.11 large seminar room

Current detection limits struggle to find exoplanets around hot (A/B-type) stars. Searching for planets in this regime provides crucial information on how planet occurrence rate scales with stellar mass. We are carrying out an interferometric survey to detect au-regime giant planets via differential astrometry orbiting individual stars of sub-arcsecond hot binary systems. The combination of milli-arcsecond resolution with stable wavelength calibration provides precision at the few tens of micro-arcsecond level in short observations at CHARA/MIRCX and VLTI/GRAVITY. This allows us to detect the wobble of a star from orbiting companions down to a few Jupiter masses. I will present the status of our survey and astrometric results, including newly detected tertiary stellar companions and some substellar candidate detections. We show that we are beginning to probe down to planetary masses on a number of targets with non-detections. This data will be used to constrain demographic models of low mass companions around hot stars.

Recent observations show that cosmic expansion is dominated by an effective cosmological constant. This means that we live inside a trapped surface, which corresponds to a Black Hole (BH) event horizon. Such Black Hole Universe (BHU) is a solution to classical GR, where two nested FLRW metrics are connected by a BH event horizon. CMB observations show some anomalies which are consistent with this BHU idea.

This new solution can be used to model our full Universe or a stellar BH inside. Observed BHs (and possibly BHs making the Dark Matter, DM) also could be made of such BHUs. In comoving coordinates the BHU is expanding while in Schwarzschild coordinates it is asymptotically static and therefore timeless. Such frame duality allows for a Perfect Cosmological Principle where spacetime can be homogeneous both in space and time, in better agreement with the relativity principle (see also darkcosmos.com)

The formation of a Solar-type planetary system is characterized by several physical processes that start with a collapsing molecular core that evolves into a protostar, a protoplanetary disk, and, eventually, a planetary system. Together with the physical evolution, a chemical evolution takes place increasing its complexity at each step (e.g., Caselli & Ceccarelli 2012, Oberg & Bergin 2021).

In particular, during the pre-collapse phase, icy mantles form on interstellar grains and start to be enriched in hydrogenated species (e.g., Taquet et al. 2012, Cuppen et al. 2017). Then, in the warm protostellar phase, the central region starts to be hot enough to sublimate the ice mantles and release the species into the gas phase, enhancing the chemical content. This warm region is identified as hot corino (Ceccarelli 2004) as it is hot (T>200K), compact (<100 au), dense (>10^7 cm^(-3)), and enriched in iCOMs (interstellar Complex Organic Molecules, Herbst & Van Dishoeck 2009, Ceccarelli et al. 2017).

Interestingly not every protostar possesses a hot corino region, and several hot corinos show very different millimeter molecular spectra.

Two main questions are still open:

- How do interstellar Complex Organic Molecules form?

- What is the origin of the observed chemical difference in Solar-type protostars?

I will briefly show some latest results obtained in the context of the IRAM/NOEMA-SOLIS and ALMA&VLA - FAUST Large Program.

Indeed, we could explore the formation pathway of some iCOMs, and investigate the hot corino nature of Solar-type protostars with very different millimeter spectra. In particular, we aim to use the complementarity between cm and mm observations to explore, on the one hand, the chemical complexity of the protostars and, on the other hand, to investigate if the observed chemical diversity is due to dust opacity effects and/or to a different grain mantle composition.

Galaxy clusters are the largest gravitationally bound structures in the universe. According to large scale structure formation scenarios, they are hierarchically formed by mergers of smaller scale structures, which are the most energetic (10^65 ergs) processes in the universe that drive shocks and turbulence into the intracluster medium (ICM). Thermodynamical properties of the X-ray emitting ICM are sensitive probes of these dynamic activities. Although we have advanced X-ray satellites to observe these phenomena, there are caveats in interpreting their data; the most challenging one being the characterization of the background. In this talk, I will present our techniques and approaches to obtain the true data of clusters of galaxies from the X-ray mission NuSTAR, which suffers from scattered light, and share the process of how we deduce the real emission on a working example of the cluster Abell 3395.

The Perseverance rover landed on the floor of an ancient martian lake on February 18, 2021. After confirming complete functionality of the rover and demonstrating the capabilities of the Ingenuity helicopter, the rover began its science investigations in earnest. The rover has now traversed almost 3 km, exploring rocks on the crater floor. Early data suggest that at least some of these rocks are lava flows with pervasive aqueous alteration. A major milestone was achieved in early September when the first samples for possible Earth return were successfully cored, sealed, and stored on the rover. I will discuss the mission's goals, activities and preliminary results.

The Vitacura science colloquia committee cordially invites all ESO staff to join an event to celebrate how ESO facilities have contributed to the Nobel Prize in Physics 2020.

Programme:

15:45 CEST/10:45 CLST -- Welcome by ESO Chile Colloquia Team (Dr. Fuyan Bian)

15:50 CEST/10:50 CLST -- Introduction by Prof. Xavier Barcons

16:00 CEST/11:00 CLST -- Talk by Prof. Pierre Léna

16:30 CEST/11:30 CLST -- Talk by Dr. Frank Eisenhauer

17:00 CEST/12:00 CLST ** Break **

17:15 CEST/12:15 CLST -- Talk by Prof. Reinhard Genzel

17:45 CEST/12:45 CLST -- Discussion session hosted by Dr. Eleonora Sani and Dr. Antoine Mérand

18:45 CEST/13:45 CLST -- End of the discussion

The jets of active galactic nuclei (AGN) can produce spectacular structures in the radio wavelengths known as a radio galaxy. The morphology and characteristics of the jets of a radio galaxy can be used as a diagnostic to understand the physics occurring within and surrounding it. In this talk, I will first present the results of several investigations of the interplay between radio AGN and their environment that use infrared (Spitzer), optical (Pan-STARRS), and radio observations (VLA, LOFAR) of AGN in massive galaxy clusters at z~1. Then, I will present a multi-wavelength study of the radio galaxy population in the galaxy cluster MOO J1507+5137, which has exceptional radio activity among the massive galaxy population. The data are suggestive that during the cluster-cluster merger phase radio activity can be dramatically enhanced. Lastly, using the radio morphology and excitation state of radio galaxies, I explore the possibility of AGN having spectral states analogous to those of X-ray binaries (XRBs) and find that different classes of radio-loud AGN occupy distinct areas of the state diagram with broad similarities to XRBs.

Turbulence is the dominant source of collisional velocities for grains with a wide range of sizes in protoplanetary disks. So far, only Kolmogorov turbulence has been considered for calculating grain collisional velocities, despite the evidence that turbulence in protoplanetary disks may be non-Kolmogorov. In this work, we present calculations of grain collisional velocities for arbitrary turbulence models characterized by power-law spectra and determined by three dimensionless parameters: the slope of the kinetic energy spectrum, the slope of the autocorrelation time, and the Reynolds number. The implications of our results are illustrated by numerical simulations of the grain size evolution for different turbulence models. We find that for the modeled cases of the Iroshnikov–Kraichnan turbulence and the turbulence induced by the magnetorotational instabilities, collisional velocities of small grains are much larger than those for the standard Kolmogorov turbulence. This leads to faster grain coagulation in the outer regions of protoplanetary disks, resulting in rapid increase of dust opacity in millimeter wavelength and possibly promoting planet formation in very young disks.

In the past decade we have started to explore extragalactic and intergalactic space using millisecond-duration radio flashes called `fast radio bursts' (FRBs).  These cosmological signals are surprisingly abundant: there is likely an FRB occurring somewhere on the sky at least once every minute.  But what is producing them?  Thanks to a new generation of wide-field radio telescopes, several FRBs per day are now being discovered.  Novel high-time-resolution observations using radio interferometers are now also pinpointing FRB locations and providing host galaxy associations.  More than a decade since the famous `Lorimer burst', we are now making rapid progress in our understanding of the enigmatic FRB phenomenon.  In this talk, I will focus on how observations with the European VLBI Network (EVN) and the Low-Frequency Array (LOFAR) are shedding light on the nature of FRB sources.  These observations have provided milli-arcsecond localisations and nanosecond-resolution polarimetry to decode the source model and emission mechanism.

Modified Newtonian dynamics (MOND) can successfully predict, without any free parameters, rotation curves or velocity dispersions of most galaxies. Nevertheless, analytic calculations suggested that globular clusters (GCs) of low-surface-brightness galaxies experience extremely strong dynamical friction in MOND. The friction would cause the GCs to quickly sink in the centers of the galaxies, which contradicts observations. The problem was underlined by the discovery of ultra-diffuse galaxies (UDGs) with large numbers of massive GCs. We therefore decided to test the MOND analytic formulas for dynamical friction by self-consistent N-body simulations of GCs moving in UDGs. It turned out that the formulas work very well as long as the GC is far from the center of the galaxy. Close to the center, dynamical friction becomes ineffective. Similar behavior had already been reported in Newtonian simulations and is called "core stalling". UDGs with GCs thus do not currently seem to pose a problem for MOND.

Protoplanetary disks are formed around protostars because of the angular momentum conservation during the protostellar collapse. Since they are the birthplace of the planets, understanding their initial conditions is essential to constrain exoplanets populations. Huge progress have been recently made in observing protoplanetary disks at the very early stages and we are now able to provide some constraints on the properties (dust mass, radius) of Class 0-I disks (Segura-Cox et al., 2018; Maury et al., 2019.; Tobin et al., 2020; Tychoniec et al., 2020). These studies suggest that young disks are compact (often < 50 au) and massive enough for planet formation (as opposed to older Class II disks, see for e.g., Manara et al. 2018). However, these properties are still quite uncertain and we lack theoretical studies that investigate disk formation as a population. Recently, Bate (2018) investigated disk population formation in massive protostellar clumps with high resolution Smoothed particle hydrodynamics (SPH) calculations but without any magnetic field. Given the magnetic field role in redistributing the angular momentum during the protostellar collapse (see for e.g. Masson et al. 2016;  Zhao et al. 2016; Wurster et al. 2016; Hennebelle et al. 2020b), it is extremely important to include it in future calculations. During this seminar, I will present our recent study (Lebreuilly et al., 2021) where we proposed the first high-resolution simulation of disk population formation from the collapse of massive protostellar clumps with non-ideal MHD using the RAMSES code (Teyssier  2002). I will show that the magnetic field and its treatment play a very important role in setting the initial disks properties. While hydrodynamical runs produce a population dominated by large disks, magnetized runs lead to half of the disks being smaller than <50 au which agrees best with observations. In addition, the magnetic field leads to a lower fraction of disk-hosting stars which suggest that even more small disks could form in simulations of higher resolution.

In the upcoming decades large facilities, such as the SKA, will provide resolved observations of the kinematics of millions of galaxies. In order to assist in the timely exploitation of these vast datasets we have explored the use of self-supervised, physics aware neural networks capable of Bayesian kinematic modelling of galaxies. In this talk I will present the network's ability to model the kinematics of cold gas in galaxies with an emphasis on recovering physical parameters and accompanying modelling errors. The models discussed are able to recover rotation curves, inclinations and disc scale lengths for both CO and HI data which match well with those estimated in the literature. The models are also able to provide modelling errors over learned parameters thanks to the application of quasi-Bayesian Monte-Carlo dropout. This work shows the promising use of machine learning and, in particular, self-supervised neural networks in the context of kinematically modelling galaxies observed using interferomers such as ALMA and VLA as well as IFU instruments like SDSS (MaNGA).

Dwarf galaxies are the most common type of galaxies in the Universe at all epochs and they play a fundamental role in cosmic history, being responsible for the build up of massive galaxies and possibly driving the reionization and metal enrichment processes. High-redshift observations of such sources are not available yet, but we demonstrate that the James Webb Space Telescope (JWST), while targeting massive Lyman Break Galaxies (LBGs), will catch for the first time the light of the faint satellite dwarf galaxies orbiting around them.We use state-of-art cosmological simulations of a typical LBG at z=6 to uncover the properties of satellite galaxies and make predictions for the upcoming JWST observations. These dwarf galaxies cover a wide range of stellar masses (log(M⋆/M⊙)≃7−9). We find that, even in such extremely dense environments, internal supernovae feedback is the key mechanism regulatingtheir evolution, capable of completely quenching dwarf galaxies. Only the frequent merger events characterising these biased regions can effectively prolong the star-formation in the most massive satellites.Modelling the galaxies’ stellar emission we reconstruct their spectral energy distributions: these reveal how with the JWST/NIRCam instrument, through colour-magnitude diagrams, it will be possible to infer properties such as the galaxies’ stellar masses and ages. The instrument’s high resolution will allow us to spatially resolve these small systems from the nearby host. Thanks to JWST’s high sensitivities we will detect, for the very first time, faint satellite dwarf galaxies of high-z LBGs in less than 5 hours.

Recent high-resolution interferometric images of submillimetre galaxies (SMGs) reveal fascinatingly complex morphologies. This raises a number of questions: how does the relative orientation of a galaxy affect its observed submillimetre emission, and does this result in an `orientation bias' in the selection and analysis of such galaxies in flux-limited cosmological surveys? In this talk I'll describe our recent paper investigating these questions, using the Simba cosmological simulation paired with the dust radiative transfer code Powderday. We found that galaxies exhibit significant scatter in their emission close to the peak of the thermal dust emission, with variation in flux density of up to ∼50 mJy at the peak. This results in an appreciable dispersion in the inferred dust temperatures and infrared luminosities (16th−84th percentile ranges of 5 K and 0.1 dex, respectively) and therefore a fundamental uncertainty in derived parameters such as dust mass and star formation rate (∼30% for the latter using simple calibrations). Using a Monte Carlo simulation we also assessed the impact of orientation on flux-limited surveys, and found a bias in the selection of SMGs towards those with face-on orientations, as well as those at lower redshifts.

We predict that the orientation bias will affect flux-limited single-dish surveys, most significantly at THz frequencies, and I will discuss how this bias should be taken into account when placing the results of targeted follow-up studies in a statistical context.

The investigation of the physical hot and energetic phenomena in the Universe will further improve our understanding of the assembly of the largest structures and massive halos of galaxies, and of the role of black holes in shaping the Universe as we see it. Spatially resolved X-ray high-resolution spectroscopy will be a crucial tool to achieve these scientific goals. The X-IFUinstrument onboard the Athena observatory will provide us with these capabilities through the use of arrays of Transition edge microcalorimeters detectors. These superconducting devices will deliver the required exquisite spectral resolution needed to achieve the core science objectives, such as the characterization of turbulence and bulk motions in the hot gaseous atmospheres of groups and clusters of galaxies in order to unveil the process of large scale structures assembly. I will present the TransitionEdge Sensors principle, the status of the instrumental development for the X-IFU instrument, and discuss their performance in view of the scientific objectives of the Athena mission. I will further present the case of a feasibility study and optimisation of the observing strategy for the characterization of the internal dynamics of the intra-cluster medium, through the use of mock simulations of observations with the X-IFU instrument.

One of the fundamental questions for planetary science is how surfaces of other planets similar to the rocky bodies in our solar system look like. What is the rock structure like? Will there be water? Are there any active atmospheric cycles? How can we detect these different conditions?The current space missions and ground based instruments allow the detection of specific gasspecies and some cloud compositions in atmospheres of giant exoplanets. With instruments  installed in the near future and space crafts currently being build or planned, these kind of observations will be available for planets with smaller sizes and an overall rocky composition. We aim to further understand the connection of the conditions of the upper atmosphere with the conditions on the crust of the planet (temperature, pressure, composition).Our equilibrium chemistry models allow us to investigate theexpected crust and near-crust-atmosphere composition based. With this, we investigate the conditions under which liquid water is actually stable at the surface of a planet and not incorporated in hydrated rocks. Based on this crust -near-crust-atmosphereinteraction we build an atmospheric model, which allows us to investigate what kind of clouds are stable and could be present in atmospheres of rocky exoplanets. This allows us to link the high altitude gas phase and cloud compositions to the surface conditions.

Black holes are solutions of Einstein's equations that were long considered unphysical.  So are white holes.  Advances in quantum gravity suggest that white holes could be generated by a quantum transition at the end of the Hawking evaporation of primordial black holes.  I illustrate the theoretical ground of this scenario and briefly discuss its possible astrophysical relevance. 

Finding a black hole, especially a nearby one, is a dream of almost every astronomer. But it is not easy as the black holes are pitch black. One of the promising methods is gravitational microlensing, in which a background source gets brighter temporarily due to its light being bent and magnified by a foreground object. Gaia space mission provides unique data which can be used for discovering black holes thanks to its superb accuracy time-series astrometric measurements. However, in order to efficiently use Gaia data, a long-term monitoring and follow-up of candidate microlensing events is necessary. I will describe our programme of coordinated time-domain observations of candidates for lensing events reported by Gaia, including long-term photometry collected by a global network of robotic and manual telescopes, as well as spectroscopic and astrometric follow-up using the largest telescopes in the world. I will conclude with the future plans for the forthcoming era of the VRO/LSST observatory as well as NRST/WFIRST and GaiaNIR space missions and their potential impact on the black hole hunt.

The host galaxies of z>6 quasars are ideal laboratories to investigate the interplay between the accreting black hole and star formation and to characterize the interstellar medium (ISM) at cosmic dawn. The unprecedented capabilities of ALMA and NOEMA have opened a new window to study the galaxy evolution at early epochs at (sub-)mm wavelengths. By surveying multiple ISM tracers, we can probe the different phases of the star-forming medium and put first quantitative constraints on their physical properties for which there is little information at such high redshifts. In this talk I will present an ALMA multi-line survey of two z>6 quasar host galaxies and their nearby serendipitous-discovered companions. These are among the most star-forming galaxies known to date at these redshifts that do not show evidence of AGN activity. By measuring the emission of various gas tracers (OH163𝜇m, H2O, mid-/high-J CO, [CI]369𝜇m, [CII]158𝜇m, [NII]205𝜇m), we study the impact of the luminous accreting black hole and intense star formation on the ISM of the quasar hosts and their companions. In addition, by combining continuum emission in different frequency bands we place constraints on the dust properties. In this talk, I will show the power of multi-line studies of far-infrared diagnostics in order to dissect the physical conditions in the first massive galaxies as they emerge at the end of the Epoch of Reionization. This study lays the foundation for a follow-up campaign using NOEMA aiming to probe the warm dense phase of the ISM at z>6.

Blue straggler stars (BSS) were originally identified in the color-magnitude diagram (CMD) of the globular cluster M3, where they defined an extension of the cluster main sequence, blueward and above the turnoff (TO). Among the variety of objects that populate stellar clusters, BSS  are surely between those still presenting many puzzles to astronomers since they are considered crucial probes for the study of the complex interaction between stellar evolution and stellar dynamics. Further, their presence poses a challenge for the standard single-star evolution theory, since stars with masses higher than that of the cluster TO  should have evolved into the white dwarf regime long ago and, besides, the major formation scenarios for  BSS involve stellar interactions. At present, these exotic stars have been largely identified in different stellar systems, such as globular clusters (GCs), dwarf galaxies, open clusters (OCs), and even in the field populations of the Milky Way. In particular,  available catalogs of  BSS in OCs are purely based on photometric criteria,  namely only the location of a given star in the CMD dictates its BS nature. Nevertheless, systematic investigations of the properties of galactic OCs are hampered by the inhomogeneity of the data available by the date of the catalogs were published, and consequently, the  BSS reported in this catalog are mostly of uncertain membership. Thus, while useful, these compilations are not reliable enough to allow the derivation of statistical properties of BSS.The principal aim of this thesis was to create a catalog of BSs in OCs based on the astrometric solutions of Gaia DR2 and not only on photometric criteria. In addition, we have searched also for possible yellow stragglers stars (YSS) i.e possible evolved BSS.  Finally, we have complement Gaia DR2 data with multi-epoch spectroscopic data from FLAMES, which allowed us to have a closer look at the BS population in four OCs with very different properties: age, metallicity, mass, and location in the MW disk.

Gamma-ray bursts are the brightest electromagnetic phenomena in the universe. They are associated with the emission of an ultra-relativistic jet following the formation of a new compact stellar object (black hole or possibly magnetar) following a cataclysmic event such as the collapse of a massive star or the merger of two neutron stars. Even if this general theoretical scenario is now well accepted, many fundamental questions remain. I will discuss several of them, related to the structure and dynamics of the jet, and to the dissipative and radiative mechanisms at work, trying to draw some consequences from the most recent observations, and in particular from the exceptional event GW170817. I will end the talk with a presentation of the SVOM multi-wavelength space mission, which will be launched in early 2023, and whose core program is dedicated to gamma-ray bursts.

Dome C in Antarctica offers exceptional conditions for time-series photometry thanks to the continuous night during the Antarctic winter and favourable atmospheric conditions. We developed a pilot project to search and characterise transiting exoplanets from this site and qualify it for visible photometry. Our instruments have been running for several years and provide excellent data. The main telescope is undergoing a major upgrade that will increase its throughput and enable simultaneous observations in two colours. I will present the project, the results, the ongoing observations, and the upgrade we are implementing.

Transition disks with large inner dust cavities are thought to host massive companions. However, the disk structure inside the companion orbit and how material flows toward an actively accreting star remain unclear. We present a high-resolution continuum study of inner disks in the cavities of 38 transition disks. Measurements of the dust mass from archival Atacama Large Millimeter/Submillimeter Array observations are combined with stellar properties and spectral energy distributions to assemble a detailed picture of the inner disk. An inner dust disk is detected in 18 of 38 disks in our sample. Of the 14 resolved disks, 8 are significantly misaligned with the outer disk. The near-infrared excess is uncorrelated with the mm-dust mass of the inner disk. The size–luminosity correlation known for protoplanetary disks is recovered for the inner disks as well, consistent with radial drift. The inner disks are depleted in dust relative to the outer disk, and their dust mass is uncorrelated with the accretion rates. This is interpreted as the result of radial drift and trapping by planets in a low α (∼10−3) disk, or a failure of the α-disk model to describe angular momentum transport and accretion. The only disk in our sample with confirmed planets in the gap, PDS 70, has an inner disk with a significantly larger radius and lower inferred gas-to-dust ratio than other disks in the sample. We hypothesize that these inner disk properties and the detection of planets are due to the gap having only been opened recently by young, actively accreting planets

The Small Magellanic Cloud (SMC) is an excellent laboratory to investigate the chemical enrichment history of a galaxy that has experienced strong gravitational interactions with other systems, since it is in an early stage of a minor merger event with theLarge Magellanic Cloud. Despite its proximity (~60 kpc) and the possibility to resolve its stellar content, the chemical composition of the SMC is still poorly known. In order to fill this gap and the accurately reconstruct the chemical evolution of the stellar populations in the SMC, we analysed FLAMES@VLT high-resolution spectra of about 200 red giant stars belonging to the SMC field. Additionally, we analysed stars members of three SMC clusters with different ages (~11, ~6 and ~1 Gyr) covering the entire range of ages of the SMC clusters system. This dataset allows to reconstruct the role played by the different contributors to the chemical enrichment, i.e. Type II and Ia supernovae, hypernovae, AGB stars.

In particular, most of the stars (both in fieldand clusters) have solar-scaled [alfa/Fe] ratios, indicating that they formed from a gas already polluted by Supernovae Type Ia. Among the field stars we identified a bunch of rare SMC metal-poor stars ([Fe/H]<-2.0) that allow to study for the first time the early chemical enrichment of the galaxy. Finally, we found the evidence of the presence of a metallicity gradient within the SMC, with metallicity decreasing moving outward

While jets were not initially anticipated by star formation models, they are clearly a fundamental feature in young stellar systems. Hundreds of jets have been observed within a few hundred parsecs at many young stars of different evolutionary stages from Class 0 to Class II. In this talk, I will present the results of two studies of protostellar jets which reveal the importance of jets at young stars. In a case study of the bipolar jet of DO Tau, I use high resolution spectro-imaging observations from Gemini/NIFS to search for jet rotation which may allow us to constrain jet launching models. I will then present high resolution images from HST/WFC3 of four Class 0/I sources. In both studies we investigate the observed jet wiggling patterns to identify the origin of the wiggling demonstrating the capability of using bipolar jets to identify the existence for planets in the earliest stages of star formation.

ALMA observations of circumstellar disks obtained by the "Disk Substractures at High Angular Resolution Project" (DSHARP) have revealed that the dust distribution in the majority of (large) circumstellar disks is characterized by small-scale structures. Dust rings are the most common features, but crescents
and spiral arms were also observed. Whereas the origin of these structures is still debated, there are many indications that they might be directly connected to the formation of planetary systems. During my talk, I will provide a quick overview of the main results obtained by DSHARP and discuss more recent studies, both theoretical and observational, that highlight the relation between disk substructures and planets.

Through their strong stellar winds, massive OB-type stars act as galactic engines, influencing star formation and galaxy evolution. The loss of mass and associated angular momentum during the life of massive stars determines their explodability and the formation of a compact object at the end of their evolution. Despite its importance, mass-loss is still one of the most elusive parameters in stellar astrophysics. The lack of understanding of the eruptive and extreme mass-loss of stars in the upper part of the HR diagram makes stellar evolutionary models highly uncertain. This is especially the case of the enigmatic Luminous Blue Variable (LBV)  stars.

In this informal discussion I will first present an overview of the upper HR diagram, focusing particularly on the instabilities and observational properties of LBV stars. I will then summarize different diagnostics (and related challenges) to estimate the mass-loss rates. I will show the importance of multiwavelength observations of the central star and associated circumstellar nebula to recover the mass-loss history. I will finally present some recent results showing the contribution of LBVs to dust in galaxies.

The first detection of gravitational waves was made in September 2015 with the measurement of the coalescence of two ~30 solar mass black holes at a distance of about 1 billion light years from Earth. The talk will provide some history and description of the detector. A review will be given of more recent measurements of black hole events as well as the first detection of the coalescence of two neutron stars and the beginning of multi-messenger astronomy. The talk will end with a discussion of some prospects for the field.

With the very recent discovery of radio luminous AGN at z>6, a new window of opportunity is finally opening in the study of the galaxy evolution at the end of the Epoch of Reionization. Our pilot programme in the 60 deg^2 GAMA-09 field uses a new selection technique taking advantage of the large frequency coverage of GLEAM by selecting compact, steep and curved sources at low-frequency (70-230MHz). Out of four candidates, one new powerful radio galaxy, 0856+0224, is confirmed at z=5.55, finally overtaking the z=5.2 20 year-old record for distant radio galaxies (albeit just falling short of the new recent z=5.7 record). Interestingly, 0856+0224 presents similarities with existing z<5 redshift samples, giving confidence in the success of our selection technique. Our recent progress on a second source, 0917-0012, thanks to the extensive multi-wavelength coverage from follow-up observations with ALMA and JVLA, supplemented with publicly available data, place this source at a promising z>5. I will also discuss the refinement of our selection technique over the full 1200 deg^2 sky area covered by the ESO VIKING near-infrared survey, leading to 55 new high-redshift candidates. This sample aims to provide us with the first statistically significant radio luminous active galactic nuclei sample at z > 6.5 during the Epoch of Reionization. The nature of radio selection presents the advantage of being insensitive to orientation-dependent obscuration, it allows us (i) to study simultaneously the co-evolution of the supermassive black hole and host galaxy and (ii) to enable the study of the IGM through the HI absorption line.

We analyze the physical conditions (density and temperature), chemical abundances, dynamics and kinematics of gas in HH529II, HH529III and HH204, photoionized Herbig-Haro objects in the Orion Nebula. By using very high resolution spectroscopy obtained withUVES@VLT, we separate the Doppler-shifted emission of the velocity outflows from the main nebular emission, studying each object independently. To study the 3D dynamics and kinematics we complement our spectroscopic study with 20 years of archival of the Hubble Space Telescope (HST) imaging. In all cases, we were able to determine the physical conditions through several diagnostics. We analyze the chemical composition by using both recombination lines (RLs) and collisional excitation lines (CELs). We studyone of the most important problems in the photoionized nebulae: the discrepancy between abundances based on CELs and RLs. In HH204 we did not observe such discrepancy, while in HH529II and HH529III we did. Despite of the different physical conditions and ionization degrees, the chemical composition of HH204, HH529II and HH529III, based on CELs is consistent, presenting abundances of metals around 0.1 dex greater than those derived in the Orion Nebula. We also found direct evidence of destruction of dust inthe shock fronts, releasing elements such as Fe, Ni and Cr in the gas phase, increasing their abundances in these objects by several times the content of the Orion Nebula. Through the radial and tangential motions, we explored the dynamics and kinematics of each outflow, concluding that HH529II is an internal working surface of the HH529 flow.

Persistent tension between low-redshift observations and the Cosmic Microwave Background radiation (CMB) suggests residual systematics or new physics beyond the standard LCDM model. In this talk, I will show results obtained from local observations of supernovae and baryon acoustic oscillations combined with low-redshift distance calibrators, that provide constraints on the Hubble constant and the sound horizon in a cosmologically independent way. When these values are compared to constraints from the CMB, a tension up to 5 sigma arises. Several modifications of LCDM have been put forward to reconcile the tension, but how well do these models actually perform? I will talk about the current status of tensions between the CMB-based and local (based on gravitational time delays and classical distance ladder) distance calibrations. I will also critically review most popular extensions of LCDM proposedto reconcile these measurements.

For more details about this work: https://arxiv.org/abs/1909.07986

To connect the composition of proto-planetary disks with that of planets it is necessary to convert molecular composition measured in disks into an elemental composition. This requires a solid knowledge of the disk and it's chemistry to do with any accuracy. At the same time it is important to spatially resolve the emission so the composition of gas around sites of planet formation can be isolated. With the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA large program, we have both the resolution as well as the ancillary information to constrain the elemental composition around planet forming gaps. I will discuss the elemental composition derived from the MAPS disks as well as the implications for planet composition. 

Festkolloquium fuer Professor Winfried Petry

The Adaptive Optics Facility (AOF) is an ESO project started in 2005, which transformed Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This has been done by replacing the conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Star (LGS) Units to its centerpiece. Additionally, two Adaptive Optics (AO) modules (GALACSI serving MUSE a 3D spectrograph, and GRAAL, serving Hawk I a wide field infrared imager) have been assembled onto the telescope Nasmyth adapters, each of them incorporating four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The complete AOF is installed on Yepun since 2017, has been fully commissioned and delivers science since 2018.

This talk will make a summary of the main drivers of the AOF project, will present the design and performance of the DSM and the 4LGSF, will give some insights about the operation of Yepun together with AOF and will finally illustrate the on-sky performance obtained during the commissioning.

In 2017 the Event Horizon Telescope (EHT) Collaboration made the first direct image of the light surrounding the black hole in M87. While spectacular, this result was just the beginning of a multitude of projects. By deepening the coverage on M87 in time and polarisation with an improved array, combining with multi-wavelength coverage, and exploring other supermassive black holes, we are building a more complete model of black holes as "central engines".

Our Galactic centre supermassive black hole Sgr A* is a major focus at the moment, but we also have results on several of the brightest nearby radio galaxies, famous for their enormous particle-accelerating plasma jets. I will provide an overview of what we have learned since the first big announcement, with an emphasis on the implications for multiwavelength/multi-messenger science, and what results are close on the horizon, literally.

Our leading model of galaxy formation hinges on strong energy injection by active galactic nuclei (AGN) powered by accreting supermassive black holes in order to explain the observed properties of galaxy populations. Even though "AGN feedback" is widely accepted as the chief source of energy operating in massive galaxies, the dominant physical mechanisms through which supermassive black holes supposedly shape galaxy evolution remain unidentified. This poor grasp of the physics underlying AGN feedback remains a major obstacle limiting (i) a conclusive assessment of the role of AGN in galaxy evolution, (ii) the interpretation and constraining power of observational data and (iii) the development of realistic models for AGN feedback in state-of-the-art cosmological simulations. In this talk, I will present results from numerical, (radiation-)hydrodynamic, cosmological simulations designed to test an array of specific AGN physical processes in massive galaxies at high-redshift (z > 2). These simulations make a strong case against "momentum-driven" feedback, ruling out direct radiation pressure from the AGN or large-scale outflows suffering strong cooling losses. The associated feedback is too weak, requiring unrealistically high black hole masses to effectively launch outflows. Our simulations single out two effective AGN feedback mechanisms. One is associated to radiation pressure arising from infrared photons trapped in dusty regions of the interstellar medium. This process has a strong impact on galactic nuclei, but can only operate effectively when AGN are highly obscured by dust. The most effective AGN feedback mechanism, I will argue, corresponds to "energy-driven" winds. Such outflows operate through hot, over-pressurised bubbles capable of ejecting gas from galaxies and of halting halo gas inflow through adiabatic expansion. The talk will conclude with a discussion on the expected observational imprints of energy-driven bubbles, an analysis of their multi-phase structure as well as its origin, and an assessment of their impact on galaxy evolution.

The merger history of a galaxy has a direct impact on the structure of its geometrically defined thick disc. Among other effects, mergers induce flaring in the stellar populations in the disc, which can be reflected on the thick disc’s age structure. As weare studying the age structure of thick discs in the MW and nearby galaxies with an unprecedented level of detail, it is important to use simulations in order to have a more comprehensible picture of the diversity of thick disc age structures, and their connection to the galaxies' merger histories.

In this talk, I will present the results of an analysis performed on a sample of 27 simulated MW mass galaxies in their cosmological context, where we explore the connection between the flaring of mono-age populations (MAPs), thick disc flaring, thin/thick disc separation, and thick disc’s age structure. I will explain under which conditions MAPs create flat thick discs, and how these galaxies form a continuum thin/thick structure, have radial age gradients, and tend to have quiescent recent merger histories, similar to our understanding of the Galaxy. Conversely, I will show the different scenarios we find where MAPs can create flared thick discs, with these galaxies showing a wider variety of the aforementioned features.

In conclusion, the results presented in this talk are in agreement with the emerging picture of thick discs being diverse and complex components of external galaxies, which when studied in detail, can provide vital constrains for the formation and evolution of disc galaxies.

The quasar model has reached relative maturity: we know that light is emitted at great power across the electromagnetic spectrum from the active nuclei of distant galaxies, where violent accretion processes release huge amounts of energy from gravitational stores. We observe that, in some quasars, matter falling onto the central black hole is funnneled into dramatic jets, emitting radio light across galactic distances. Over cosmic history the quasar population peaked in unison with star formation activity, leading us to suspect the role of quasars in the quenching of star-formation. Missing from the picture, however, is a full understanding of how such feedback processes manifest in the vast majority of quasars: those objects with very little radio emission. In these 'radio-quiet' quasars, jets appear to be absent, and it is possible that the faint radio signal that we do detect is the result either of smaller-scale AGN activity, of continued star formation, or of both. Only by undestanding the source of this very faint emission can we fully understand the quasar stage of galaxy evolution. This talk presents findings using strong gravitational lenses as 'cosmic telescopes' that magnify distant source structure, allowing us to resolve these intriguing objects to the sub-parsec scale.

Because they are dark-matter dominated, dwarf galaxies provide some of the most stringent tests of our cold dark matter model. Specifically, Lambda CDM makes predictions about the number, shape, and spatial distributions of the faint friends of massive galaxies. I will present results from the Exploration of Local VolumE Satellites (ELVES) survey, that constructs the largest sample of satellites around Milky Way-like hosts. Our ability to utilize dwarfs as tests of CDM is limited by our understanding of baryonic process; I will also discuss our efforts to us the Hyper Suprime Camera Survey to understand the role of feedback and merging in dwarf evolution. If time permits, I discuss what we know about black holes in dwarf galaxies, and how their demographics sheds light on the formation of the seeds of supermassive black holes.

I begin with a bird's eye view of the recent progress on the EFT for black hole inspirals, with an emphasis on the key role played by gravity loop amplitudes. I then present some work in progress on an alternative approach to the problem. In this alternative approach, the classical scattering angle emerges from the phase shifts of a QM scattering problem. I present a proof-of-principle of this method by reproducing the scattering angle of a probe mass in the backgrounds of a Schwarzschild BH and NUT space, to all-orders in the Post Minkowskian expansion. I end with some thoughts on how to generalize this method beyond the probe limit - with an emphasis on Extreme Mass Ratio Inspirals accessible to LISA.

Astrophysical jets are frequently observed phenomena in the Universe, which play an important feedback role in the evolution of their host systems. Long-term monitoring of post-AGB binary systems has revealed periodic variations in their Balmer lines, indicating that jets are also common in these systems. To harness the wealth of information hidden in these observations, we developed a spatio-kinematic model of the jet to recreate the observed Balmer line variations. I will present our results for 15 jet-creating post-AGB binaries, where we determined the full 3D, velocity, and density structure of the jets and their mass-outflow momenta. I will also present how these results can be linked to the mass-transfer in the binary system, which reveals that the circumbinary disk feeds the accretion onto the jet-launching companion. With this work, we gain crucial insights into the structures of jets launched by these post-AGB binary systems and their mass-transfer history.​

Cepheid stars play a considerable role as astronomical distances indicators thanks to the empirical relation between their pulsation period and intrinsic luminosity: the PL relation. The uncertainty on this relation is the largest contributor to the error budget of the Hubble constant, that describes the Universe's expansion. The value of the Hubble constant is currently at the center of a major controversy: while it is estimated at 67.4 +/-0.5 km/s/Mpc by the Planck satellite, the local measurement based on Cepheids is larger by 4 sigma, with a value of 74.0 +/-1.4 km/s/Mpc. This discrepancy may provide evidence for physics beyond the standard model: it is therefore critical to improve the PL calibration with precise and accurate distance measurements of Cepheids.

In 2018, the second data release of the Gaia satellite (Gaia DR2) provided parallaxes for 1.3 billion stars with an unprecedented precision. However, Cepheids are bright stars and are often saturated in detectors. Moreover, the variations in brightness and color that occurs for variable stars like Cepheids are not yet taken into account in the Gaia data reduction. Therefore, Cepheids parallaxes can be affected by systematics due to their photometric variability.

In order to avoid these issues, a solution is to find stable and faint companion stars in the close environment of Cepheids. Using 36 indirect, unbiased and accurate distances based on Gaia DR2, I calibrate the PL relation and revise a previous value of the Hubble constant based on HST measurements of Galactic Cepheids.

Our Milky Way still hosts remnants from the era of first star formation in the form of (very) metal-poor stars, which we can study in detail. They are useful to learn about the First Stars and the conditions in the early Universe, and they provide unique insights into the early formation and evolution of our Galaxy. Metal-poor stars are typically searched for in the Galactic halo and the dwarf galaxies surrounding the Milky Way. However, a prediction of simulations is that the fraction of metal-poor stars that are very old is highest towards the centers of galaxies: in their bulges.

The task of finding the most metal-poor stars in the inner Milky Way faces many challenges, including large dust extinction, severe crowding and a high average metallicity of the dominant stellar population in the bulge. In this talk, I will present the Pristine Inner Galaxy Survey (PIGS) which has reached unprecedented efficiency in finding metal-poor stars in the bulge region, employing metallicity-sensitive photometry to select candidates for spectroscopic follow-up.

For the first time, using PIGS, we can study the the kinematics of thousands of (very) metal-poor inner Galaxy stars, and investigate the occurrence of the chemically peculiar carbon-enhanced metal-poor (CEMP) stars in this region. I will present these results and discuss what they can teach us about the origin of the oldest component of our Galaxy.

Water is a key molecule in star and planet forming regions. Recent water line observations toward several low-mass protostars suggest low water gas fractional abundances in the inner warm envelopes. Water destruction by X-rays has been proposed to influence the water abundances in these regions, but the detailed chemistry, including the nature of alternative oxygen carriers, is not yet understood.

In this study, we aim to understand the impact of X-rays on the composition of low-mass protostellar envelopes, focusing specifically on water and related oxygen bearing species. We compute the chemical composition of two low-mass protostellar envelopes using a 1D gas-grain chemical reaction network, under various X-ray field strengths. According to our calculations, outside the water snowline, the water gas abundance increases with X-ray luminosities. Inside the water snowline, water maintains a high abundance of ~10^-4 for small X-ray luminosities, with water and CO being the dominant oxygen carriers. For large X-ray luminosities, the water gas abundances significantly decrease just inside the water snowline (~10^-8 - 10^-7) and in the innermost regions (~10^-6). For these cases, the O2 and O gas abundances reach ~10^-4 within the water snowline, and they become the dominant oxygen carriers. The HCO+ and CH3OH abundances, which have been used as tracers of the water snowline, significantly increase/decrease within the water snowline, respectively, as the X-ray fluxes become larger. The abundances of some other dominant molecules, such as CO2, OH, CH4, HCN, and NH3, are also affected by strong X-ray fields, especially within their own snowlines. These X-ray effects are larger in lower density envelope models. Future observations of water and related molecules (using e.g., ALMA and ngVLA) will access the regions around protostars where such X-ray induced chemistry is effective.

Galaxies evolve under the influence of gas exchanges with their surrounding gaseous halos, the so-called circumgalactic medium (CGM), extending over tens of kpc. A solid characterisation of both galactic gas flows and chemical composition of the CGM is thus crucial to understand galaxy evolution, especially in the first few Gyrs of cosmic time, when galaxies rapidly assembled their masses and reached their chemical maturity.  I will review recent studies on galactic feedback and CGM metal enrichment in the early Universe, mainly exploiting ALMA observations of galaxies at z>4. These works find evidence that star-formation-driven outflows and (in case of dense environments) tidal stripping can efficiently contribute to the metal pollution of the CGM, as suggested by the detection of large [CII]-halos extended on ~20 kpc around massive galaxies. Also, I will discuss pros and cons of the currently adopted observational techniques, the importance of cosmological simulations in guiding the interpretation, and some of the possibilities offered by future telescopes for improving our understanding of the baryon cycle in early galaxies.

Galaxy mergers play an important role in how galaxies evolve over time, however extragalactic astronomers do not yet totally understand the process by which those mergers happen.

The brightest galaxies of groups and clusters are extremely luminous galaxies, usually located in the centres of those systems –central galaxies. Simulations predict that these central galaxies have undergone more mergers than other similarly luminous galaxies, making them an excellent test of the merger process. The recent merger history of galaxies can be read through their stellar population gradients. Central galaxies with active merger histories are predicted to have shallower metallicity gradients than satellite galaxies of a similar mass. We examined the stellar population gradients (age, metallicity and alpha-element abundance ratios) of central galaxies in the SAMI galaxy survey to determine whether they are offset from similarly massive satellite galaxies in order to reach a better understanding of the role of mergers in galaxy formation and evolution.

Astronomical observations with ground-based telescopes are affected by differential atmospheric dispersion, a consequence of the wavelength-dependent index of refraction of the atmosphere. In high resolution astronomical instruments, an Atmospheric Dispersion Corrector (ADC) is mandatory to avoid wavelength dependent losses. Even though an ADC seems a simple component, but from the design phase to on-sky commissioning, several problems can occur. The design of an ADC is based on atmospheric models that, to the best of our knowledge, were never tested on-sky. Different models shows a variation of 50 milli-arcseconds (mas), a value close to the required residuals from current ADCs. During the commissioning, detecting a variation of 50 mas in a PSF of 1 arcseconds, is not an easy task. We will present a method to measure on-sky the atmospheric dispersion based on measuring the PSF centroid of each wavelength using cross-dispersed spectra. We are able to characterize different atmospheric models with an accuracy of 18 mas. As for the on-sky commissioning, we present a simple concept based on the ellipse fit of intensity contour plots of the PSF. This method will allow us to better align the ADC in terms of prisms angles and total dispersion direction using on-sky measurements. In this talk we show the study we did to improve the phases of an ADC from design to on-sky commissioning.

Planets form in disks around young stars. The resulting planet compositions are intimately linked to the disk chemical structures; the distribution of molecules across disks regulate the elemental compositions of planets, including C/N/O/S ratios and metallicity (O/H and C/H), as well as access to water and prebiotically relevant organics. These molecules are in part inherited from earlier stages of star formation, and in part formed in situ in disks. In this talk I will present our developing view of the molecular cloud and protostellar chemistry that sets the initial chemical conditions in planet forming disks. I will then turn to recent gains made in our understanding of disk chemistry through the Molecules with ALMA at Planet-forming Scales (MAPS) ALMA Large Program. With MAPS we have been exploring disk chemical structures down to 10 au scales in a small sample of disks in which dust substructures are detected and planet formation appears to be ongoing. Some highlights include discoveries of links between dust and chemical sub-structures, large reservoirs of nitriles and other prebiotically interesting organics in the inner disk regions, and elevated C/O ratios across most disks. I will discuss how these results are reshaping our view of the chemistry of planet formation, but also review some open questions that remain and the observations, models and laboratory experiments that will be needed to address them.

Nowadays, the development of the observational instruments is so high that became very sensitive to the details of stellar physics. The interpretation of the stellar surfaces images, the fundamental parameters, the stellar variability and the hosting planet detection & characterisation needs realist simulations of stellar convection. In this context, three-­dimensional radiative hydrodynamics simulations of cool stars are essential to a proper and quantitative analysis of these observations. I will present how these simulations across the Hertzsprung-Russel diagram have been (and will be) crucial to prepare and interpret the spectrophotometric, interferometric, astrometric, and imaging observations.

Paper: https://arxiv.org/pdf/2105.03430.pdf

Complex organic molecules (COMs) are of particular astrochemical importance as they are the precursors of prebiotic molecules. Therefore, the search for COMs in Class II protoplanetary disks, where planetary systems are forming, is of great interest. A COM of particular significance is methanol (CH3OH), which is a feedstock for building molecules of higher complexity. CH3OH primarily forms at low temperatures (< 20K) on the surface of icy dust grains. In this talk, I will present the first robust detection of CH3OH in a warm Herbig Ae/Be disk with ALMA Cycle 7 observations. I will discuss the chemical origin of CH3OH in this disk, and the implications regarding our understanding of the origins of chemical complexity in disks in general.

A new window into the growth and evolution of large-scale structure has opened up with the recent observations of the thermal and kinetic Sunyaev-Zel’dovich (SZ) effects. I will review recent observations of the SZ signals and highlight their expected rapid growth over the next decade with upcoming cosmic microwave background experiments, like Simons Observatory and CMB-S4. I will present ongoing work to extract SZ signals in data from the Atacama Cosmology Telescope and how they can be used to constrain the important baryonic process that govern galaxy formation. Time permitting, I will conclude by discussing the connections between these SZ observations and mitigating the modeling uncertainties associated with "baryonic effects" in future large-scale structure surveys like LSST.

Paper: https://arxiv.org/abs/2105.04224

I will present the results of a unique multi-wavelength campaigns focused on the recently discovered LMXB Swift J1858. This system displayed extreme variability in both X-ray and optical bands, similar to the famous black hole binary V404 Cyg during its 2015 outburst. Our observations covered the full frequency range from X-ray to radio and were provided by observatories including XMM-Newton, NuSTAR, NICER, VLTs, Gemini, GTC, VLA, MeerKAT and HST. A key feature of the campaign is a 4-hour window during which we obtained time-resolved, strictly simultaneous observations across the whole electromagnetic spectrum.

I will walk you through the findings obtained by monitoring programs of independent instruments, then we will step back into a multi-wavelength perspective to get insights in the geometry of the system and the physical mechanism driving its outflows, unveiled thanks to the unprecedented coordination of several major observatories across the globe. We will finish with an overview of the findings of the system and how coordinated multi-wavelength campaigns can help us to understand the physics of compact objects and how they interact with their environment.

All of the survey data products will be made available to the scientific community in a ready-to-use format accompanied by practical examples.

Brown dwarfs are a critical link between the realms of stars and planets. Their formation process is one of the crucial missing pieces in our understanding of how star and planet formation work. Understanding the origin of brown dwarfs is the main motivation for recent deep studies of star-forming regions and young clusters. The major question driving our studies is whether the birth environmentaffects their formation efficiency, as predicted in several formation scenarios. The expectation is that high gas or stellar densities or the presence of massive OB stars may be factors that boost the incidence of newly formed brown dwarfs with respect tostars. To address this question we investigate the stellar and sub-stellar objects in the drastically different environments of massive young clusters RCW 38 and NGC 2244 and that of nearby star-forming regions. Here we will present the current status ofyoung brown dwarf studies, compare the low-mass Initial Mass Functions in a variety of Milky Way environments. For RCW38, we will address the high-mass IMF and the shallow slope that we see in the center (mass segregation or not?). We will summarised theimplications of these results for our understanding of sub-stellar formation processes.

PESSTO, the Public ESO Spectroscopic Survey of Transient Objects (and its successors) has been in operation for almost 10 years. This collaboration brought together a significant fraction of the ESO extra-galactic transient community, with current membership standing at more than 250. During the last decade of operation, PESSTO and other teams have significantly changed the way transient detection, selection and followup is achieved. This has made such observations more efficient, but was also required following the significant increase in transient discovery rate. At the heart of PESSTO operations is the Marshall - this ingests transient detection information and is used to prioritise objects for spectroscopic classification and followup.

In this talk I will briefly discuss the history of supernova detections: from individuals eye-balling photographic plates to community 'brokers' automatically filtering thousands of possible new transients each night. I will then outline the PESSTO collaboration and its operations with specific focus on how the Marshall enables efficient operations, collaboration, and scientific return. I end with an outlook of how transient science will evolve in the next decade with the arrival of the LSST among other surveys.

With the help of the APOGEE survey and Gaia EDR3, we review the dependency of metallicity and alpha-elements with orbital parameters and velocities for an unprecedented coverage and precise sample of stars in the inner Galaxy (28 000 stars within |XGal| < 5 kpc, |YGal| < 3.5 kpc, |ZGal| < 1 kpc, and 8000 stars more restricted to the innermost regions). These samples allow us to characterize the different coexisting populations in the region via joint analysis of the distributions of velocities, metallicities, orbital parameters and chemical abundances.  The chemo-kinematic data dissected on the orbital plane maps the bar, the inner disk, and the pressure supported component, showing that the Galactic bar consists of metal-poor and metal-rich stars. It clearly shows that all these components are much more complex and that the classical definitions of the galactic components are blurred.  We also detect a tail of counter-rotating stars, suggesting a merger or proto Galactic disk remnants. The analysis would not have been possible without the high-resolution spectroscopic survey APOGEE, the parallaxes and proper motions from Gaia EDR3, and the StarHorse tool, which can combine spectra, photometry and astrometry to derive precise distances even for this challenging area.

Paper: https://arxiv.org/pdf/2103.01236.pdf

Nuclear star clusters (NSCs) are extremely dense stellar systems that reside in the centres of ~70% of galaxies, including our Milky Way. This nucleation fraction even reaches > 90% forgalaxy masses ~ 10^9 M_sun. NSCs have similar sizes to globular clusters (GCs), but are even more massive and dense. NSCs often co-exist with supermassive black holes and follow distinct scaling relations with properties of the host galaxy, but it is stilldebated how NSCs form and grow. Generally, two main scenarios are discusse: in-situ from gas at the galactic centre or via the dissipationless accretion of GCs that spiral inwards due to dynamical friction. Most likely, a mixture of both pathways is realized in nature, but the dominant channel nor how it relates with the host galaxy are known.

Constraining NSC formation in galaxies requires a complete view of both thekinematics and chemical properties of the host galaxy, the NSC, and the GC system. Sucha study is challenging, but possible with modern day integral-field spectroscopy. I will present how MUSE can be used to determine the dominant NSC formation channel for individual galaxies, in conjunction with a semi-analytical model of NSC formation. These complementary approaches reveal for the first time how the NSC formation depends on properties of the host galaxy and show a transition of NSC formation via GC-inspiral to in-situ star formation with increasing NSC mass.

The formation of supermassive black holes (MBH) is thought to be tightly linked to the formation and growth of their host galaxy bulges. MBH mass measurements of local galaxies based on stellar or gaseous motion reveal strong correlations of the MBH mass with bulge properties, such as bulge mass, stellar velocity dispersion and light concentration. However, the black hole sample and its covered mass range are limited, revealing an increased scatter for the high and low mass end of the scaling relations. While it is crucial to expand and constrain these regions in order to investigate on the universality of the scaling relations for different galaxy populations and possible different galaxy formation scenarios, the MBH measurements are challenging due to the need of time-expensive (preferable IFU) data and resolution arguments.

I present my dynamical MBH measurements of almost 20 galaxies expanding on both the high and low mass end of the scaling relations. For our measurements we made wide use of IFU data, such as SINFONI, NIFS, MUSE, ALMA, and more. We tooks special care in testing dynamical measurement methods on different tracers (stars vs gas) and other systematics. I will also discuss formation scenarios of galaxies harbouring strongly undermassive black holes or possibly no black holes at all. A strong tool to give implications about the formation and growth of MBHs is the analysis of the galaxy's central orbital distributions. I will conclude my talk with a discussion on what we can learn from examining orbital distributions in galaxy evolution and formation context and how measurement uncertainties are affecting our MBH results.

Dense cores within molecular clouds are the places where stars are formed and the final place where turbulence is dissipated. Several (large) programs have focused on the dense gas kinematics to constrain the angular momentum on dense cores, however, little has been done to understand the effect of magnetic fields on ions (affected by magnetic fields) when compared to neutrals. It is expected (based on several theoretical arguments) that the non-thermal velocity dispersion (a.k.a. turbulence) should be narrower both for molecular ions (compared to neutrals) when the magnetic field inside the core is static. A few of the previous observations of starless cores and IRDCs have shown suggestive evidence for broader linewidths in ions, however, it remained unexplained. I will discuss the new opportunities to study the gas kinematics of ions and neutrals, and their implications for star-formation. I will show the results of comparing 8arcsec angular resolution maps of N2H+ (1-0) and the NH3 (1,1) and (2,2) in the dense core Barnard 5. Surprisingly, the non-thermal velocity dispersion of the ion is subsonic and systematically higher than that of the neutral by ~20%. We explore a new and surprising possibility, that the magnetic field inside dense cores is not static, but oscillating. And, the ions should be more strongly dynamically coupled to this oscillating field than the neutrals, thus accounting for their broader linewidth.

The study of high-redshift galaxies is key to our global understanding of galaxy formation and evolution. In particular, the interstellar medium (ISM) is a critical component of the complex interplay between the accretion of baryons, the physics that drives the buildup of stars out of this gas, the subsequent chemical evolution and feedback processes, and the reionisation of the Universe. ALMA offers an unprecendented combination of sensitivity, spatial resolution and frequency coverage in the millimetric (mm) and sub-mm domain. Together, these powerful capabilities have transformed our understanding of the (sub)mm extraglactic sky, enabled detailed studies the ISM of the highest-redshift galaxies and redefined our view of the global dust and gas properties of the Universe over large look-back times. These discoveries have in turn both triggered and provided new constraints on theoretical models of galaxy formation and evolution in the early Universe. In this talk, I will highlight some of the ALMA results that have shaped this new era in studies of the cold and distant Universe.

Evolved stars and their winds play a crucial role for galactic chemical evolution, including the origin of building blocks for planets and life. Essential chemical elements, like carbon, are produced inside these stars, transported to the surface by turbulent gas flows, and ejected into interstellar space by massive outflows of gas and dust. I will present an overview of recent results and ongoing work on stellar winds. In particular, I will describe how project EXWINGS contributes to the field, creating global dynamical star-and-wind-in-a-box simulations. With such models it will be possible to follow the flow of matter, in full 3D geometry, all the way from the turbulent, pulsating interior of an asymptotic giant branch star, through its atmosphere and dust formation zone into the region where the wind is accelerated by radiation pressure on dust. Advanced instruments, which can resolve the stellar atmospheres where the winds originate, provide essential data for testing the models. I will also discuss what the recent dimming event of Betelgeuse may teach us about the still enigmatic mechanisms that drive the winds of red supergiant stars.

ESO is regularly updating its science-driven perspective with the goal to provide the best facilities and services for its community. As part of this exercise, ESO polled its users between January and February 2020. Questions were inspired by the previous poll (Primas et al. 2015), to probe any evolution of community opinions and profile, with an emphasis on the future of the VLT/I - following the “VLT in 2030” workshop (Mérand & Leibundgut, 2019). Of 14,000 registered unique users polled, from the ESO and European ALMA portals, 1,674 complete responses were received, a response rate comparable to the 2015 poll. The present poll was split into three parts: 1) profile of respondents; 2) current and future observing facilities; 3) ESO in the coming decade.

I will present the main results of the polls which will appear in the upcoming issue of the ESO Messenger.

Paper: https://arxiv.org/abs/2104.06431

Despite the importance of massive stars and star clusters for the energy content, stellar population and evolution of galaxies, the mechanism that ignites their formation in molecular clouds is still poorly addressed. Infrared Dark Clouds (IRDCs) are the likely precursors of massive stars. It has been suggested that IRDC formation and dynamical processing by multiple shock episodes triggered by bubbles, such as HII regions and Supernova Remnants (SNRs), can efficiently initiate star formation within these clouds. It is thus important to understand the conditions of density and temperature set by large-scale shocks in IRDCs to constrain the ignition of star formation in these objects. In this work, I will present the large scale shock triggered by the SNR W44 in the IRDC G034. I will show how the shock, probed by Silicon Monoxide (SiO) and observed with ALMA, enhances the density of the processed gas to values compatible with those required for massive star formation and has helped to shape the cloud. Thanks to the high resolution achieved by ALMA, the internal physical structure of the shock was resolved for the first time, providing a direct test to Magneto-Hydro-Dynamic (MHD) shock theories. Moved by these results, we have initiated the large single-dish observing program SHREC, aimed to observe SiO(2-1) emission in SNRs interacting with molecular clouds. During the talk, I will briefly introduce the aim and technical aspects of SHREC and present preliminary results obtained toward the SNRs IC443 and W41.

Over the past decades, several important steps have been taken to understand the formation and evolution of first generations of galaxies. In particular, thanks to deep multi-wavelength observations by Hubble Space Telescope (HST), studies of early galaxies have now been pushed well into the Epoch of Reionization, i.e. up to z~10-11 only 500Myr after the Big Bang (e.g. Bouwens+15, Oesch+16, Atek+18). However, our current knowledge beyond z~2-3 is significantly biased to the rest-frame ultraviolet observations as it’s only accessible by deep optical/near-infrared observations, and dust-obscured properties of high-redshift galaxies hasremained mostly unknown. This situation was revolutionized by extremely sensitive and high-resolution far-infrared (FIR) interferometers such as ALMA and NOEMA. First ALMA observations showed us surprises by finding fainter FIR emission than expected fromlow-redshift galaxy observations, suggesting an evolution of dust-obscured galaxy properties at high-redshift (e.g. Capak+15, Bouwens+16). To understand this potential evolution with statistical sample and with wide range of galaxy parameters, large ALMA observations were required. In this talk, I will discuss the evolution of dust attenuation and dust-obscured star-formation of galaxies at z~3 to z~6 revealed by ALMA, including a recent ALMA large program: ALPINE and an on-going large program: REBELS.

Supernovae are explosive endpoints of stellar evolution. The most common two categories are core-collapse supernovae and thermonuclear supernovae. For core-collapse supernovae, the kinetic energy of the explosion is provided by the gravitational energy release when the iron core of an evolved massive star collapses to either a neutron star or a black hole. Open questions include how stripped supernovae lose their envelopes and which core-collapse supernovae make black holes and which make neutron stars.

In part I of my talk, I will present examples of how optical integral field observations of the remnants of certain core-collapse supernovae, such as 1E0102.2-7219 or Puppis A, provide us with puzzling new structures that need to be understood if we want make progress on the nature of their progenitors. For thermonuclear supernovae, the energy source is explosive nuclear fusion in white dwarf stars of lighter elements like helium, carbon, and oxygen, to heavier elements like silicon or nickel and iron. What kind of white dwarfs explode and how they evolve to ignition are still largely open questions.

In part II of my talk, I will present the recently discovered optical coronal line emission of the reverse shocked ejecta in three young thermonuclear (Type Ia) supernova remnants and discuss a new approach how these optical emission lines can be modelled to infer key parameters of the original supernova, such as explosion energy and mass.

Relic galaxies, i.e., massive, compact and old galaxies which have formed most of their stars in a short time are the remnants of high-z red nuggets. Most of the high-z galaxies are supposed to merge with smaller companions and systematically increase their size becoming the big monsters in the local Universe. But, due to the stochastic nature of galaxy mergers, few of them should survive untouched for their entire life, these are the relics. The time has finally come: although extremely rare, it is now possible to find them and study their properties in very details. They will provide a unique look at the high-z red nuggets, the stellar populations in the cores of the largest local galaxies and the role of mergers and environment on the evolution of the most massive and passive galaxies.

I will bring you through the "Relics' revolution", starting from the discoveries of the first relic galaxies in the local Universe, and then I discuss our contribution to the field. KiDS@VST survey and a campaign of spectroscopic follow-ups have provided us with an unprecedented sample of relic candidates, the so called ultra-compact galaxies (UCMGs), i.e. galaxies with stellar masses > 8 * 10^10 solar masses, and sizes < 1.5 kpc, at redshifts z < 0.5. We have studied their abundance in terms of redshift and environment.

We are now approaching the innermost cave, with the INSPIRE large program, which aims at determining, within the UCMG sample, the stellar populations of relic candidates using XShooter@VLT. The first results of this project, i.e. stellar population parameters and velocity dispersions for 19 relic candidates, are reported in recent works. Thanks to INSPIRE, we seize the sword: we confirm the discovery of the first 10 relics ever found at 0.15 < z < 0.4, which add to the only three existing in the local Universe and already characterized in very detail. I will finally go through the current state of our project and future prospects.

Paper: https://arxiv.org/pdf/2103.06045.pdf

Class III stars are those in star forming regions without large non-photospheric infrared emission, suggesting their protoplanetary discs have only recently dispersed. As part of the first dedicated ALMA study, 30 class III stars in the 1-3 Myr Lupus region were observed, resulting in 4 sub-mm detections attributed to circumstellar dust (Lovell+21a). This disc population was shown to be diverse: with possible young debris discs, remnant low-mass protoplanetary discs, and inner hot excesses, each pointing at different processes in operation during this era. In a follow-up study of the gas kinematics of the 1 source detected with CO gas (NO Lup), this was shown to be outflowing: unique for a star at this stage of evolution (Lovell+21b).

In this talk I will discuss the results of these two studies in the context of other published and ongoing work, and why future studies to constrain planetesimal formation timescales and disc evolution require further analysis of class III stars, in both Lupus and other young star forming regions.

Mini-symposium on galaxy and QSO evolution

Monday, April 26th, 14:00 - 15:00 (CEST)

14:00 Characterising the host galaxy ISM of the very first quasar, Katy Proctor (UWA, Australia)

14:20 Modelling the emission of galaxies an AGN from the radio to the X-rays, Laura Martinez Ramirez (UIS / UC, Colombia)

14:40 Uncovering AGNs in statistical samples of quiescent galaxies, Bruno Rodriguez Marquina (PUCP, Perú)

The impact of bars in the evolution of their host galaxies has been studied for over 50 years. Many studies in this field now becoming mature have shown that to fully understand galaxy evolution (including our own Milky Way) it is imperative to understand how bars form and evolve, and in what ways and circumstances they can alter the evolution of the host galaxy. In this hopefully pedagogical talk, I will provide an overview of the current answers to these questions, with theoretical and observational work. This overview will include the effect of environment, the downsizing picture of bar formation, and the connection between bars and bulges and the feeding of AGN.

In the last decade we have explored the cosmic depths and found a statistically significant number of galaxies well into the Epoch of Reionization. However, our physical knowledge of these pristine objects remains very scant. Investigating the internal structure, interstellar medium and evolution of early galaxies is the next challenge to understand key processes as the cosmic history of baryons, feedback, reionization and metal enrichment of the intergalactic medium, This ambitious plan can be tackled by combining a new generation of physically-rich, high resolution, zoom simulations with data in the sub-mm bands provided by ALMA. This approach will be soon strengthened by the forthcoming JWST power. I will review the present status and the open questions in the field.

I will offer an informal discussion on the Observatory Operations during the pandemic. What are the constraints we operate under? How do we decide the level at which we operate? How do we deal with Covid cases on-site? What lessons have we learnt up to now? ‘Your questions’...

Massive black holes at the centers of galaxies can launch powerful wide-angle winds, which if sustained over time, can unbind the gas from the stellar bulges of galaxies. These winds, also known as ultra-fast outflows (UFOs), may be responsible for the observed scaling relation between the masses of the central black holes and the velocity dispersions of stars in galactic bulges. Propagating through the galaxy, the wind should interact with the interstellar medium creating a strong shock, similar to those observed in supernovae explosions, which is able to accelerate charged particles to high energies. In this talk I'll present the Fermi Large Area Telescope detection of gamma-rayemission from these shocks in a small sample of galaxies exhibiting energetic winds. The detection implies that energetic black-hole winds transfer ~0.04% of their mechanical power to gamma rays and that the gamma-ray emission represents the onset of the wind-host interaction.

Massive stars play a critical role in the evolution of galaxies and star clusters. Recent observations of the latter have highlighted the need for systematic studies dedicated to probing the impact of massive stellar evolution on the properties of stellar populations. While the use of fitting formulae to stellar tracks remains a popular choice for modelling stellar evolution in population synthesis codes, these formulae are not adaptable to changes. In this talk, I will discuss and present results from an alternative approach, one that is more adaptable: Method of Interpolation for Single Star Evolution (METISSE). It can readily make use of stellar models computed with different stellar evolution codes and compare their predictions for populations of stars. Using METISSE with data from different stellar evolution codes, I will show how various physical ingredients used in the evolution of massive stars, such as the treatment of their radiation dominated envelopes, can lead to differences in their evolutionary properties. I will discuss the implications of these differences on the evolution and interaction of stars inbinaries, and how they can impact compact binary mergers and the properties of gravitational wave events.

Magnetic fields thread our Milky Way Galaxy, influencing interstellar physics from cosmic ray propagation to star formation. The magnetic interstellar medium is also a formidable foreground for experimental cosmology, particularly for the quest to find signatures of inflation in the polarized cosmic microwave background (CMB). Despite its importance across scientific realms, the structure of the Galactic magnetic field is not well understood. Observational tracers like polarized dust emission yield only sky-projected, distance-integrated measurements of the three-dimensional magnetic structure. I will discuss new ways to probe interstellar magnetism in three dimensions, by combining high-resolution observations of Galactic neutral hydrogen with recent insights into how gas morphology encodes properties of the ambient magnetic field. These 3D maps are a new tool for understanding the magnetic interstellar medium and the polarized foreground to the CMB.

Carbon is next to H, He, and O, the most abundant element in the Universe and is extensively used (usually in combination with O) when probing the  chemical evolution of stellar populations and galaxies. However, the origin of carbon is not yet settled and some studies favor low-mass stars while others favor high-mass stars. The situation is further complicated as the surface composition of carbon in evolved stars might have been altered by the internal burning processes of the star. Therefore, reliable carbon abundances  that trace the composition of carbon of the gas cloud the star was born from requires spectral analysis of un-evolved dwarf and subgiant stars.

In this talk I will present new measurements of carbon in a sample of 91 microlensed dwarf and subgiant stars in the Galactic bulge and discuss how we can use these to probe the origin and evolution of the Galactic bulge as well as some hints of which stars that are the main contributors to the C enrichment of the interstellar medium.

https://arxiv.org/pdf/2103.09122.pdf

Despite the long history of dark matter, its nature is still unknown.Cold dark matter (CDM) remains the generally accepted workinghypothesis.  Apparent shortcomings in the ability of CDM to explainvarious observations have been noted and have led to the development ofalternative hypotheses, but so far none have been able to dethrone CDM. This is partly due to the presence of baryons in galaxies, whose feedback processes and radiative properties are far more complex thanthe physics of dark matter. In the presence of baryonic feedback, many dark-matter models start losing their distinctive profiles, leaving usunable to distinguish between them.

One promising way out of this conundrum is to study dark matter in environments with as few baryons as possible. Ultra-faint dwarf galaxies (UFDs) are the faintest, least massive, and most dark matter–dominated galaxies known. They are predicted to have dark-matter distributions unchanged by baryonic feedback.

In this colloquium I will present the current state of research to constrain the nature and properties of dark matter using UFDs, includingthe first results from a novel 100-hour MUSE survey of UFDs. I will address the constraints on primordial black holes from their dynamical effects on stellar distributions, as well as the constraints on various types of particulate dark matter (weakly interacting massive particles, axion-like particles, self-interacting dark matter, and fuzzy dark matter) from emission-line searches and the first determined dark matter–density profile of a UFD. I will end with an outlook for the near future of this field.

Bars are a major driver of secular evolution in disc galaxies, promoting the inflow of gas to the centre, where stellar structures, such as nuclear discs are built. We constrain the formation of these structures by deriving their stellar kinematics and mean population properties. To this end, we use observations with unprecedented spatial resolution, obtained with the MUSE integral-field spectrograph for a sample of 21 Milky Way-type galaxies in the local Universe. We show that nuclear discs are characterised by a high rotational support, i.e. near-circular orbits with low velocity dispersions, and are significantly younger, more metal-rich, and less [α/Fe]-enhanced, as compared to their surroundings. These findings are consistent with the picture of bar-driven secular evolution and contrast with the formation of old and kinematically hot classical bulges in violent accretion events. Moreover, nuclear discs exhibit well-defined radial gradients of the population properties with single slopes, suggesting that they are continuous components from their outer edge to the galaxy centre. We argue that these continuous (stellar) nuclear discs may form from a series of bar-built (gas-rich) nuclear rings that grow in radius, as the bar evolves. In this picture, nuclearrings are simply the star-forming outer edge of nuclear discs. Finally, we do not find evidence for the presence of classical bulges in the centres of these galaxies. This could result from feedback processes efficiently preventing the formation of classical bulges or may challenge the paradigm of hierarchical structure formation, questions we will address in a dedicated MUSE survey.

Recent sub-arcsecond resolution surveys of the dust continuum emission from nearby protoplanetary disks, showed a strong correlation between the sizes and luminosities of the disks. We aim to explain the origin of the size-luminosity relation (SLR) between the 68 effective radius of disks with their continuum luminosity, with models of gas and dust evolution. We use a large grid of models with and without planetary gaps, varying the initial conditions of the key parameters. We calculate the disk continuum emission and the effective radius for all models as a function of time. By selecting those simulations that continuously follow the SLR, we can derive constraints on the input parameters of the models. We show that a larger fraction of disks populates the SLR if planetary gaps are present but they tend to follow a different relation than smooth disks. We derive a SLR for disks with strong substructure. Furthermore, we find that the opacity model and the grain porosity affects drastically the evolution of disks on the size-luminosity diagram where relatively compact grains that include amorphous carbon are favoured. Moreover, disks on the SLR show a preference for high disk mass and low turbulence-parameter α-values.

SRG spacecraft with German (eRosita) and Russian (ART-XC) X-Ray telescopes was launched by RosKosmos on July 13th of 2019 from Baikonur. During the flight to the L2 point of the Sun-Earth system SRG performed calibrations and long duration Perfomance Verification (PV) observations of a dozen of targets and deep fields. Starting in the middle of December 2019, the SRG scanned the whole sky in half a year and discovered more than a million point X-Ray sources, mainly AGNs and QSOs, stars with hot and bright coronae, and 16 thousand clusters of galaxies. There is a competition and synergy with the search for clusters of galaxies by Atacama Cosmology and South Pole Telescopes sensitive in the microwave spectral band.

We see X-Rays from hundreds of the stars accompanied with exoplanets.

SRG provided the X-Ray map of the whole sky in hard and soft bands, the last is now the best among existing. It reveals a lot of information about the distribution of absorbing gas in the Milky Way and provides a beautiful image of the North Polar Spur and similar bright emitting eRosita Bubble on the Southern side from the Central Part of the Galaxy. I plan to describe the Observatory plans for the future and to demonstrate several exciting results from the PV phase observations as well as from the second and third all-sky survey which is ongoing. The huge samples of the X-ray selected quasars at the redshifts up to z=6.2 and clusters of galaxies will be used for well-known cosmological tests and for detailed study of the growth of the large scale structure of the Universe during and after reionization.  

During all sky survey SRG/eRosita is discovering every day several extragalactic objects which increased or decreased their brightness more than 5-10 times during half of the year after previous scan of the same strip on sky. Significant part of these objects has observational properties similar to the Tidal Disruption Events. 

The dynamical properties of bars in disc galaxies — such as their rotation (or pattern) speed — are sensitive to the attributes of their dark matter halos. In particular, it has been shown that dynamical friction induced by a massive dark matter halo will slow down the rotation of bars. Numerous observational studies have found that bars tend to rotate fast, suggesting that the stellar component is dominant over the dark matter in the inner regions of barred galaxies. On the other hand, numerical simulations within the LCDM framework tend to find that bars slow down excessively. This has given rise to a tension between fast bars and the LCDM cosmological paradigm. In this informal discussion I will give a historical overview of this tension, and show recent results from cosmological simulations that offer clues on how to solve it.

Paper: https://arxiv.org/pdf/2103.14048.pdf

Since the first direct detection in 2015, gravitational waves havecompletely changed the landscape of known stellar mass black holes(BH). This gives unprecedented constraints on the evolution and deathof the most massive stars, which are otherwise hard to study dueto their rarity. In particular, stellar evolution predicts theexistence of a gap in the BH mass distribution, due topair-instability evolution. Its location between ~45-125 Msun is oneof the most robust predictions of stellar theory, primarily sensitiveonly to uncertain nuclear reaction rates. This will allow for the useof gravitational-wave detectors as nuclear astrophysicsexperiments. On the other hand, ~3% of the population of BHs inferredhave masses within the pair-instability gap. Explaining these BHsrequires either dynamics, gas accretion, or exoticphysics.

Pair-instability should also produce visible electromagnetictransient, however, an uncontroversial detection is stilllacking. Upcoming large time-domain surveys will soon be able toreveal even very rare transients and should identify these.

In this talk, I will review the physics of (pulsational) pair-instability inthe context of the latest gravitational-wave and time-domainsurveys. I will show the wide range of theoretical predictions andtheir trends with stellar mass, and highlight what we have alreadylearned from the binary BH mergers detected. Finally, I will discuss possible ways to populate the pair-instability gap andpotential open problems with some of the scenarios that have been
proposed.

Most massive stars spend their lives in so close orbit with a companion star that severe mass exchange or even coalescence is inevitable as the stars evolve and swell. A third of massive stars are thus stripped of their fluffy, hydrogen-rich envelopes, leaving the compact helium core exposed. These stripped stars are so hot that most of their radiation is emitted in the ionizing regime. Using evolutionary and spectral models of stripped stars, I will show how they sometimes dominate the ionizing emission from full stellar populations and even significantly contribute to cosmic reionization. With their hard ionizing spectra, stripped stars possibly leave observable traces, for example in the nebular spectrum of distant galaxies. Apart from being ionizing sources, stripped stars are also interesting to consider as gravitational wave emitters. Creating a population model, we predict that several stripped stars orbiting compact objects will be detectable by LISA.

Star formation in massive clusters is a major route of star formation, particularly in extreme environments as encountered in starburst galaxies or in the early universe. In these environments an intimate relation between massive reservoirs of gas and the population of young stars can be expected, among them numerous hot and luminous early type stars.

These stars will have a profound impact on the surrounding gas, via their UV radiation, winds, and ultimately via supernova explosions. It is not clear, however, what the consequences of this impact will be. Further star formation could be triggered, suppressed, or ultimately terminated by feedback, and the physical conditions of the dense gas forming new stars can be changed, possibly changing the fragmentation properties and the resulting stellar mass function.

We here present an APEX study of the temperature distribution within the dense gas reservoir in the NGC3603 region. NGC3603 harbours the most massive young cluster associated with substantial amounts of molecular gas known in our Galaxy and may serve as a template for its more massive extragalactic counterparts.

We find a clear gradient in dense gas temperatures, decreasing with distance from the starburst cluster, testifying to the potential of a starburst cluster to skew the outcome of further star formation in its environment . Major sites of ongoing massive star formation are found at the far ends of the giant molecular cloud, indicating that indeed the story in NGC3603 goes on.

Paper: https://arxiv.org/pdf/2103.12135.pdf

In the last five years ALMA revolutionised our comprehension of planet formation. The first breakthrough was delivered by the impacting images of the rings and gaps in protoplanetary disks, providing the first direct evidence of planet formation in fieri. On the other hand, ALMA is revolutionising also our comprehension of the disk chemistry, which is crucial to answer another key question about planet formation: what chemical composition planets inherit from their natal environment?
Answering this question is the goal of the ALMA-DOT project, the ALMA chemical survey of Disk-Outflow sources in Taurus.

I will show a few recent results obtained in the context of the ALMA-DOT survey, which allows us to characterise the chemical structure of disks and to investigate the chemical path from protostars to planets.

One of the key aim of the modern astronomy is to understand how galaxies formed and evolved. In this framework, the Milky Way is an excellent testing ground for galaxy formation and evolution theories. The branch of astronomy that studies the history of our Galaxy is the Galactic archaeology. With the advent of large-scale surveys, we are able to produce a detailed mapping of the structural, dynamical chemical, and age distributions of the Milky Way stellar populations. Indeed, combining data from large spectroscopic surveys and Gaia data will allow us to disentangle the full chemo-dynamical history of our Galaxy. In this talk, I will discuss what the Galactic archaeology is, the impact of large-scale surveys on this field and my current work in Galactic archaeology to date stars using chemical clocks.

Over the last decade precision measurements of the cosmic microwave background and the large scale distribution of galaxies have made it possible to use cosmology to probe many aspects of particle physics. Perhaps the prime example is neutrino physics. For example, because neutrinos have a profound impact on how structures form in the Universe, cosmological observations can be used to probe the neutrino mass with high precision. In the talk I will review the status of cosmology as a tool for probing the physics of neutrinos and other weakly interacting particles. I will also outline the future of the field, with particular focus on upcoming projects such as EUCLID and LSST.

Wide-field extragalactic surveys have revealed a population of extremely luminous Lyman-alpha emitters observed at the end stages of reionisation (z>6). These objects represent the phase in the life of massive galaxies when they experience their most luminous star-burst and/or supermassive blackhole accretion event before the onset of significant dust production. Currently, spatially resolved observations of these galaxies allow us to probe the emission from young stars, the interstellar medium and the properties of surrounding hydrogen gas. I will present spatially resolved (spectroscopic) follow-up studies of lluminous galaxies at z>6 with ALMA, HST/WFC3 and MUSE on the VLT. We find that these galaxies likely reside in early ionised bubbles and are complex systems, consisting of multiple components where traces of metals and outflows are already present. I will address the difficulty in addressing the nature of the ionising sources and discuss in particular the unique value of ALMA observations, even when JWST and the ELTs will be available.

Paper: https://arxiv.org/abs/2103.07958

The ultimate goal in galaxy studies is to have a complete picture of galaxy formation and evolution across the history of the Universe. A robust determination of the abundance of massive (even quiescent) galaxies at high-redshift is essential to constrain current galaxy formation models.

In this context, this work addresses the challenge of studying the build-up of massive galaxies adding a new population of optically faint (HST-dark) Balmer Break Galaxies (BBGs), which are bright at longer wavelengths (even in the sub-mm regime), to the general population of massive galaxies at z > 3. We study in detail the physical properties of the general population of known massive galaxies at z > 3 and we analyze the sample of BBGs by comparing them with a mass-limited (M > 10^10M☉and z > 3) sample and a color-selected (H −[3.6] > 2.5) sample extracted from the CANDELS catalogs published for these fields.

We have therefore detected a new population of previously unknown optically dark massive red galaxies and provide a more complete sample of the general population of massive galaxies at z > 3. This population of massive distant galaxies may represent the progenitors of most massive local galaxies. In the context of the current paradigm of galaxy formation, it is essential to constrain and confirm the number density of high redshift massive galaxies, which will provide crucial information to expand our understanding of galaxy evolution. The existence of this numerous population of massive galaxies at high redshifts represents a challenge for existing cosmological models and state-of-the-art simulations.

In a cosmological setting, the disk of a galaxy is expected to continuously experience gravitational torques and perturbations from a variety of sources, which can cause the disc to wobble, flare and warp. Specifically, the study of galactic warps and their dynamical nature can potentially reveal key information on the formation history of galaxies and the mass distribution of their halos. Our Milky Way presents a unique case study for galactic warps, thanks to detailed knowledge of its stellar distribution and kinematics. Using a simple model of how the warp’s orientation is changing with time, we measure the precession rate of the Milky Way’s warp using 12 million giant stars from Gaia Data Release 2, finding that it is precessing at 10.86 ± 0.03 (statistical) ± 3.20 (systematic) km/s/kpc in the direction of Galactic rotation, about one third the angular rotation velocity at the Sun’s position in the Galaxy. The direction and magnitude of the warp’s precession rate favour the scenario that the warp is the result of a recent or ongoing encounter with a satellite galaxy, rather than the relic of the ancient assembly history of the Galaxy. Using N-body simulations, we analyse the vertical response of the Galactic disc to the repeated impacts of a satellite similar to the Sagittarius dwarf galaxy, finding that the instantaneous vertical pattern speeds in the disc have a constraining power in the context of a Milky Way-satellite interaction.

Our standard model for physical cosmology, with its nonbaryonic dark matter and cosmological constant, passes well-checked tests that make a persuasive case that this model is a good approximation to reality. There are open issues, of course, and research programs in progress to address them. I will discuss some less widely advertised issues that I suspect merit closer attention.

Will a newborn star feel a difference between being born in Orion today, and in a massive, dusty galaxy 10 billion years ago? Forming stars at rates 100x higher than any present-day galaxy, the dust-enshrouded, sub-mm bright galaxies (SMGs) play a key role in the stellar mass assembly in the early Universe. However, our understanding of physical conditions in the star-forming regions in SMGs has been very limited, chiefly due to the coarse (> 1 kpc) resolution of mm-wave observations. Even with the full power of ALMA, multi-tracer (dust, [CII], CO) studies of the ISM in SMGs remain an extremely expensive undertaking.

I will present the recent results of molecular gas studies of probably the best-studied SMG: SDP.81 (z = 3.0), a spectacular, strongly gravitationally lensed starburst. Combining ∼40 hours of ALMA long-baseline, multi-band observations, lens modelling, and radiative transfer models, we mapped the physical conditions in this SMG at an unprecedented, ∼100 pc resolution. These results provide the first view of the physical conditions in SMGs on scales comparable to nearby galaxies and their variation on sub-kpc scales. I will also discuss the limitations of the current data, on-going VLA and ALMA studies targeting the HCN, HCO+ and radio emission in this unique source, and future survey of ISM physics of large samples of SMGs.

Paper: https://ui.adsabs.harvard.edu/abs/2021MNRAS.501..347A/abstract

I present results from high-resolution, "genetically modified", cosmological simulations quantifying the diversity in the structural properties of faint dwarf galaxies.

Ultra-faint dwarf galaxies are the least luminous objects in the Universe. Their shallow potential well makes them highly sensitive to the interaction between dynamical mass growth and internal, feedback processes. Thissensitivity provides an ideal laboratory for testing galaxy formation models, while also generating significant scatter in their stellar and gaseous properties. Quantifying the expected scatter will be essential to interpret findings in the next generation of deep, wide sky, surveys (e.g. LSST).

To begin this quantification, I present a suite of simulated low-mass, field dwarf galaxies, evolved with cosmological zoom simulations capable of resolving the explosions of individual supernovae (Rey et al. 2019, 2020). These high-resolution simulations are complemented with the "genetic modification" approach, allowing us to resimulate chosen galaxies making targeted changes to their cosmological mass growth history.This unique combination of abilities providesa complete overview of the interaction between feedback and assembly in these systems.

I will show how this interplay regulates the ability of the lowest-mass galaxies to accrete fresh gas at late times, leading to diverse cold gas content at similar stellar masses. I will further show how this accretion can allow dwarfs to re-ignite and sustain continuous, low levels of star formation until today, highly reminiscent of observed star-forming low-mass dwarfs (e.g. Leo T, Leo P).

One of the most intriguing outcomes of the young field of exoplanet research is the emergence of highly-irradiated planets, located much closer to their host star than any of the Solar System planets. These planets, which give us a glimpse into the future of our Solar System once the Sun reaches its final life stages, have been studied in-depth, allowing us to learn more about their temperature profiles and present molecules and atoms. However, the characterisation of atmospheric dynamics, a crucial part totruly understand an atmosphere, has severely lagged behind.

Until recently, our only glimpse into the winds on exoplanets was restricted to global circulation models (e.g. Showman et al. 2009, Parmentier et al. 2018), probing only the lowest layers of the atmosphere, and atmospheric escape models, which describe the mass outflow far out in the exosphere (e.g. Lecavelier des Etangs et al. 2010, Bourrier et al. 2017). Thanks to these techniques, we know that the lower atmosphere is dominated by zonal winds,while the exosphere expands into space. But what happens in the vast area between these regimes?

This pressing question has been answered in my PhD work, where I, for the first time, utilise resolved spectral lines which probe the missing layers of the atmosphere to understand their atmospheric dynamics (Seidel et al. 2019, 2020a, 2020d submitted). During my talk, I will present a consolidated view of highly-irradiated exoplanet atmosphere dynamics, focussing on the connection between the different atmospheric layers.

Since planets are formed in disk around young stars, the structure of disks have a direct impact on the formation of planetary bodies. The inner disk regions are of particular interest, and these are also the regions where magnetohydrodynamic winds, capable of affecting the disk evolution, are launched. To spatially and simultaneously resolve infall, early disk evolution and outflow launching, we are using ALMA in its largest configurations. The first resolved images of wind launching from a disk were reported towards the Class I source TMC1A, where we also report evidence of early grain growth and that the bulk of the planet forming material is being delivered to the disk from the envelope, unaltered. Included in the study, is also the Class 0 system B335. The observations allow us to constrain the ejection process on the smallest scales, as well as the accretion from the envelope on all relevant scales. We are also currently developing a machine learning algorithm to search through the ALMA archive and classify the dust distribution around young protostellar disks. This is to address the question of whether winds can carry away significant amounts of dust from the disk itself.

Scientists generally aim to discover general principles which apply to the phenomena or systems they study. The most general principles, called laws, often require at least one parameter - a constant - in order to relate observations to the theoretical framework. The values of these constants are generally not predicted by any theory but have to be experimentally determined instead. I will speak about how constants relate to our understanding of physics and how fundamental constants can be used to study cosmology, higher-dimensional theories, and constrain dark energy models.

In the context of UN WOMEN theme for International Women’s Day, “Women in leadership: Achieving an equal future in a COVID-19 world”, the presentation will be focused on the impact of COVID-19 has had on women worldwide. The crisis caused by the pandemic has demonstrated the great challenges we have as societies, making gender inequalities more evident: women are the most affected by the increase in unemployment, violence, poverty, and the overload of unpaid care.  
 
In this scenario, recovery efforts must put women at the centre, joining efforts to address the immediate needs of women, ensure their livelihoods, decent work and the generation of jobs and economic opportunities, especially for those groups of women most affected by the crisis.

I will report on some of the results emerging from the ALMA large program ASPECS that obtained deep (sub-)millimeter imaging of the Hubble Ultra-Deep Field (H-UDF). The observations provide a census of dust and molecular gas in the H-UDF, down to masses that are typical of main-sequence galaxies at redshifts 1-3. The resulting data enable a great range of studies, from the characterisation of individual galaxies, capitalizing on the unique multi-wavelength database available for the H-UDF, to CO excitation studies that constrain the gas properties. Stacking analyses in dust continuum and CO line emission, using available H-UDF galaxy catalogues and precise redshifts from VLT/MUSE, helped to constrain the emission of galaxy samples that are too faint to be detected individually. The nature of the observations (full ALMA spectral scans) provides a census of dust and molecular gas in the cosmic volume defined by the H-UDF. The resulting cosmic molecular gas density as a function of redshift shows an order of magnitude decrease from z~2 to z=0. This is markably different from the atomic gas phase that shows a rather flat redshift dependence. With other measurements from the literature, these results are used to put additional observational constraints on the gas (net) accretion flows, needed to explain the build-up of stellar mass in galaxies, and are compared to cosmological galaxy formation simulations.  

The detection of phosphine (PH3), a pre-biotic molecule, in the atmosphere of Venus was published on Nature. This paper got a lot of attention from the press, due to the interesting implications for the possible presence of life on Venus in September 2020. The publication was then followed by a series of other papers questioning either the detection of the PH3 line or its interpretation. In this Informal Discussion we would like to summarize the Saga of the detection of PH3 on Venus and give some detail on the reprocessing of the ALMA data, that have been re-reduced and re-ingested in the ALMA Archive in November 2020.

Paper: https://arxiv.org/abs/2103.00016

The bright Lyman-α (Lyα) line is a key observable in studies of galaxies in the early Universe. Lyα emitters (LAEs) are, by selection, in the very first stages of their formation. The Lyα line profile is a tracer of the escape fraction of ionising photons and the Lyα equivalent width and escape fraction trace the evolution of the neutral fraction of intergalactic gas. However, empirically, the Lyα production, escape and the line profile emerging from the ISM are poorly understood at high-redshift due to thetypical limited spectral resolution and the lack of rest-frame optical spectra. Currently, cosmic noon (z~2) is the ideal redshift to study LAEs in detail. These galaxies resemble galaxies in the very early Universe with their similarly short formation times, extreme emission-lines and sizes. Importantly, the rest-frame optical lines are still observable from the ground at z~2. In my talk, I will present the first results of the ‘XLS-z2’ survey which is based on ~100 hours of VLT/X-SHOOTER observations of 30 LAEs at z~2 with stellar masses ~10^9 Msun. I will present the properties of the ISM and stellar populations that can be derived from their average UV to optical SED. I will focus in particular on the diversity in Lyα line profiles and what these tell us about the structure of the ISM in young distant galaxies. Finally, I will discuss the implications for the role of galaxies in the epoch of reionisation.

I present the Stromlo Stellar Tracks, a set of stellar evolutionary tracks, computed by modifying the Modules for Experiments in Stellar Astrophysics (MESA) 1D stellar evolution package, to fit the Galactic Concordance abundances for hot massive Main-Sequence stars. Until now, all stellar evolution tracks are computed at solar, scaled-solar, or alpha-element enhanced abundances, and none of these models correctly represent the Galactic Concordance abundances at different metallicities. This paper is the first implementation of Galactic Concordance abundances to the stellar evolution models. The Stromlo tracks cover massive stars (10<Msun<300) with varying rotations evolved from the pre-main sequence to the end of Carbon burning. I find that the implementation of Galactic Concordance abundances is critical for the evolution of main-sequence, massive hot stars in order to estimate accurate stellar outputs (L, T, g), which, in turn, have a significant impact on determining the ionizing photon luminosity budgets.I additionally support prior findings of the importance that rotation plays on the evolution of massive stars and their ionizing budget. The evolutionary tracks for our Galactic Concordance abundance scaling provide a more physically motivated approach than simple uniform abundance scaling with metallicity for the analysis of HII regions and have considerable implications in determining nebular emission lines and metallicity. Therefore, it is important to refine the existing stellar evolutionary models forcomprehensive high-redshift extragalactic studies.

The merging rate of double neutron stars (DNS) has a great impact on many astrophysical issues, including the interpretation of gravitational waves signals, of the short Gamma Ray Bursts (GRBs), and of the chemical properties of stars in galaxies. Such rate depends on the distribution of the delay times (DDT) of the merging events. In this paper we derive a theoretical DDT of merging DNS following from the characteristics of the clock controlling their evolution. We show that the shape of the DDT is  governed by a few key parameters, primarily the lower limit and the slope of the distribution of the separation of the DNS systems at birth. With a parametric approach we investigate on the observational constraints on the DDT from the cosmic rate of short GRBs and the Europium to Iron ratio in Milky Way stars, taken as tracer of the products of the explosion. We find that the local rate of DNS merging requires that $\sim 1 \%$ of neutron stars progenitors live in binary systems which end their evolution as merging DNS within a Hubble time. The redshift distribution of short GRBs does not yet provide a strong constraint on the shape of the DDT, although the best fitting models have a shallow DDT. The chemical pattern in Milky Way stars requires an additional source of Europium besides the products from merging DNS, which weakens the related  requirement on the DDT. At  present both constraints can be matched with the same DDT for merging DNS.

High-mass stars inject a large amount of energy and momentum -stellar feedback -into the interstellar medium (ISM) during their relatively short lifetimes. The feedback from these stars can influence the ISM both locally (<1pc) and across their entire host galaxy (~1kpc), and occurs through a variety of feedback processes; e.g. protostellar outflows, stellar winds, ionizing radiation. The most important of these feedback mechanisms for the overall energy and momentum budget of ISM occurs at the end of thestars lifetime, when they explode as supernovae. However, the efficiency with which SNe couple with their environment strongly depends on their local gas density distribution. Hence, the early pre-SNe feedback processes from high-mass stars play a crucialrole in setting this environment into which SNe later explode, and, therefore, in effect limit the efficiency of SNe feedback. In this talk, I will discuss our recent efforts in a quantitative study of pre-SNe feedback mechanisms within both the centre Milky Way, and a large sample of nearby extragalactic systems. In these analyses, we focus on the balance of various internal and external pressures within young HII regions. The study of the Galactic Centre represents the first such study in a high-pressureenvironment, which has important implications for high-redshift environments. The study of extragalactic systems is the first to attempt such a study on a statistically significant sample of HII regions (>2000). Together, these make key advancements in our understanding of young stellar feedback as a function of environment.

Many galaxies in the local Universe do not live alone, but in groups or even clusters. With many galaxies in little space, as well as the presence of a hot intracluster medium (ICM), the evolution of these galaxies is different from their isolated counterparts. In particular, galaxy clusters host a relatively high number of passive galaxies. Several mechanisms play a role in this, related tothe ICM (e.g. ram pressure stripping) or the galaxy number density (e.g. galaxy-galaxy interactions). That these mechanisms affect the atomic gas in galaxies (HI) is well known. However, whether it also affects the more tightly bound and centrally locatedmolecular gas (H2) is less obvious. In this talk I will present results from the ALMA Fornax Cluster Survey (AlFoCS), an ALMA survey of the CO in Fornax cluster galaxies. I will discuss the molecular gas content in these galaxies, show resolved images of its morphology and kinematics, and show how it differs from galaxies in the field at fixed stellar mass. Furthermore, I will present results from the collaboration I lead between AlFoCS and the MUSE survey Fornax3D, in which we exploit the powers of ALMA and MUSE to study the resolved star formation relation (Kennicutt-Schmidt relation) in Fornax galaxies. Lastly, I will show some surprising recent results of a study of gas-to-dust ratios in the Fornax cluster compared to the Virgo cluster and the field, using data from ALMA, Herschel, ATCA, and MUSE.

Surveys of protoplanetary discs indicate that evolved discs have dust masses that are depleted when compared to very young discs. A mechanism to deplete protoplanetary discs of dust is the radial drift of dust, the rate of which is affected by the grain size. However, measurements of grain sizes show a discrepancy between results derived using the dust emission spectral index, which find maximum sizes of mm-cm, and measurements of the degree of dust continuum polarisation, which indicate a maximum grain size of ~100 microns. I will talk about a paper where we used a population synthesis model to investigate the role of radial drift in the draining of dust in evolving protoplanetary discs. We found that the observed dust depletion is consistent with radial drift of pebbles under the assumption that they quickly grow to 100 microns and do not grow larger.

Since the 1st invention of coronagraphy in early 1900 to observe the Sun's corona, recently they have become a key technology for direct imaging of exoplanets. In this talk, I will cover the working of most common coronagraphs, how to quantify them, and factors affecting their performance. I will also talk about coronagraphic results obtained with the NEAR experiment and HCI performance of the 1st gen. ELT instrument METIS.

Astrophysical observations at (sub-)mm wavelengths (λ from ~300 μm to ~3mm) allow us to study the cold and dense material in the Universe, hence probing the formation of stars and planets, and the interstellar and circumgalactic medium within galaxies across cosmic time. The current generation of 10-meter-class single dish telescopes has delivered some of the first surveys at (sub-)mm wavelengths, allowing us to go far beyond the previously optical-biased view of the Universe. Follow-up observations with interferometers then revealed in exquisite detail the morphology and kinematics of such (sub-)mm sources, enabling tests and revisions of theoretical models for the formation and evolution of planets, stars, and galaxies. However, it is now clear that without a transformative change in the capabilities of single-dish facilities in the 2030s, interferometers (like the ALMA observatory) will soon become source-starved. The current generation of 10-m class single dish telescopes, with their limited fields of view, spatial resolutions, and sensitivities, can only reveal the ‘tip of the iceberg’ of the (sub-)mm source population, both for Galactic and extragalactic studies. These limitations cannot be fully mitigated by interferometers, which are all intrinsically affected by a low mapping speed and by the loss of diffuse extended signals.

The Atacama Large Aperture Submillimeter telescope (AtLAST; http://atlast-telescope.org/; https://ui.adsabs.harvard.edu/abs/2020SPIE11445E..2FK/abstract) project is a concept for a 50-meter diameter single dish observatory to be built near the ALMA site. With its extremely large field of view (the goal is ~ 2 degrees), spatial resolution (up to ~1.5” at 350 μm), and sensitivity to both point sources and large-scale structures, AtLAST will be transformational for all fields of Astronomy in the 2030s. Here we will describe the recently approved EU Horizon2020 project to deliver a comprehensive design study for such a next-generation single-single dish facility. AtLAST is community-driven, so get involved!

https://arxiv.org/abs/2102.06459

In this talk I will present one of most recent papers of the TIMER project with MUSE at the VLT. We have obtained high signal-to-noise and spatial resolution integral-field spectroscopy data of the inner few kpc of 21 nearby massive barred galaxies, allowing studies of the stellar kinematics and population properties with unprecedented spatial resolution. We establish the presence of nuclear discs in virtually all galaxies and show that their kinematics and structural properties are consistent with the bar-driven secular evolution picture for their formation. We also show that such nuclear discs are recovered as exponential, photometric "bulges" in careful, state-of-the-art image decompositions. Finally, I put these observations in the context of recent results concerning the central region of our own Milky Way.

https://arxiv.org/pdf/2102.00778.pdf

The properties of the most massive galaxies in the Universe provide fundamental constraints on both galaxy evolution physics and cosmology. However, extracting subtle physical properties, such as galaxy star formation histories (SFHs) and metallicities, from observations is highly challenging, owing to the age-metallicity-dust degeneracy in galaxy spectral shapes and the challenges involved in obtaining high-SNR, well calibrated spectroscopy.

I will discuss past, present and future efforts to constrain the physical properties of massive quiescent galaxies, and what these tell us about galaxy evolution. In particular I will present results from the VANDELS ESO Public Spectroscopic Survey (arXiv:1903.11082), reporting the analysis of 75 high-SNR rest-UV spectra for massive quiescent galaxies at 1.0 < z < 1.3 to extract detailed SFHs using a sophisticated Bayesian statistical approach. I will then discuss ongoing efforts to constrain the stellar metallicities of these galaxies with rest-optical KMOS observations, allowing us to probe the evolution of the stellar mass-metallicity relation across 9 Gyr of cosmic history.

Finally, I will discuss the prospectsfor furthering our understanding with upcoming instrumentation. The Multi-Object Optical and Near-infrared Spectrograph (MOONS) for the VLT will provide a million high quality spectra at z~1, and I am heavily involved in preparations for the ~200 night extragalactic GTO survey MOONRISE. I will also discuss our first steps towards learning about the earliest quiescent galaxies at z > 3 (arXiv:2001.11975), a field that will be revolutionised by the upcoming James Webb Space Telescope.

One of the most important tools to investigate the chemical history of our Galaxy and our own Solar System is to measure the isotopic fractionation of chemical elements. This is the process that distributes the less abundant stable isotopes of an element in different molecules. The isotopic ratios are governed by two main processes: 1. chemical evolution of the whole Galaxy due to stellar nucleosynthesis; and 2. local fractionation effects.For the case of nitrogen (N), the 14N/15N isotopic ratio found for the proto-Solar nebula, 440, is significantly higher than that measured in pristine Solar System materials, like comets (around 140). This suggests a local chemical enrichment of 15N during the Solar System formation. However, the causes of the 15N-enrichment are still uncertain.In this talk I will briefly review the state-of-the-art of the astronomical observations and theoretical chemical models devoted to the study of nitrogen fractionation. I will show the overall behavior of the 14N/15N ratio across the Galaxy. In particular, based on a large survey of star-forming regions, we have confirmed that the 14N/15N ratio increases with thegalactocentric distance. This overall trend can be explained by nucleosynthesis Galactic chemical evolution models.Furthermore, I will present the first interferometric maps of N-fractionation of N2H+ towards a star-forming region. Our results highlight the importance of local effects, and in particular of isotope-selective photodissociation of N2, in determining the 15N-enrichments in star-forming regions.

Complex organic molecules (COMs) are of great interest in planet-forming regions as they are potential prebiotic molecules. Detecting COMs in the protoplanetary disk phase is challenging and thus we search for precursors. Formaldehyde is commonly linked to the COM methanol as it is a precursor in the CO hydrogenation pathway. However, formaldehyde also possess gas-phase formation channels. The ortho-to-para ratio is said to distinguish between these two different formation pathways. In this talk I will show results and interpretation of ALMA observation which for the first time show a radially resolved ortho-to-para ratio profile in a protoplanetary disk.

The Adaptive Optics Facility (AOF) is an upgrade of Yepun (UT4), one of the 8m Unit Telescopes of the Paranal Observatory. The purpose of this project was to turn out Yepun into an Adaptive Telescope, by replacing the classical secondary mirror of the telescope with a Deformable Secondary Mirror (DSM) and by installing 4 Laser Guide Star Units to the mechanical structure of the telescope. In parallel to this development, two Adaptive Optics (AO) modules have been designed and installed on the telescope: GRAAL associated to HAWK-I a wide field IR imager, and GALACSI associated to MUSE a 3D spectrograph working in the visible. The AOF is working at the VLT since end 2016 and is allowing HAWK-I and MUSE to routinely deliver science. ERIS, featuring both an imager and a spectrograph, will be soon commissioned at the Cassegrain focus of Yepun while MAVIS, a large field of view instrument working in the visible, is currently designed and will be installed at the Nasmyth A of Yepun. Both instruments will make an intensive use of the AOF.

Online public talk to celebrate Women in Astronomy

the event is organised by the Max Planck Institute for Extraterrestrial Physics to mark the International Day of Women and Girls in Science

On the occasion of the International Day of Women and Girls in Science, The Max Planck Institute for Extraterrestrial Physics (MPE) is organising its annual free event "Women in Astronomy" on 11 February 2021 at 19:00, this year hosted online by the ESO Supernova Planetarium & Visitor Centre. The MPE actively promotes equal opportunities for women and girls in science. The aim is to promote the share of women in science, technology, engineering and mathematics (STEM), where they are still underrepresented.

This year, the event will feature a presentation from Dr. Suzanna Randall, astronomer at the European Southern Observatory (ESO), about her participation in the Astronautin campaign.

Ever since she was a child, Suzanna Randall was fascinated by space with its endless expenses. She wanted to find out everything about it and even to fl there herself! So, as a young adult, she decided to study astrophysics. She now works as a scientist at ESO, where she works for the ALMA telescope. Actually her dream job - but then she saw an advertisement that would change her life: "Astrononaut wanted!".

Four years later she was in the middle of training - part of the private space start-up "Die Astronautin" - with the aim of becoming the first female German to fly to the International Space Station (ISS). She will report on the tough selection process, the fun and challenges of the training and, of course, the mission. It's not just about the journey into space, but also about encouraging girls and women, in particular, to venture into the traditionally male-dominated areas of natural sciences and technology - and literally reach for the stars!

The talk will be delivered in the German language only and will be streamed live on Thursday 11 February at 19:00. It can be viewed on Youtube at this link https://youtu.be/0loymFeFwIc.

Massive black holes weighing from a few thousands to tens of billions of solar masses inhabit the centers of today’s galaxies, including our own Milky Way. Massive black holes also shone as quasars in the past, with the earliest detected a mere one billion years after the Big Bang. Massive black holes during their cosmic evolution interact with diverse environments, starting from messy and rapidly evolving galaxies at high redshift to quiescent galaxies today. I will discuss how these changing environments affect the growth of massive black holes and the formation of massive black hole binaries that eventually coalesce by emission of gravitational waves, which can be detected with ESA’s planned satellite LISA and with Pulsar Timing Arrays.

Paper: https://arxiv.org/abs/2009.01335

I present theoretical work done using the AMR MHD code FLASH on the formation of binary stars and the evolution of their discs in these systems. I simulated the collapse of molecular cores until the formation of protostars and followed the early evolution of these systems. I investigated the influence that binarity has on the global evolution of a young stellar system, including looking at mechanisms such as accretion of material, jets and outflows, and dynamical interactions. I find that while in some scenarios binary stars may produce hostile environments for planet formation via the destruction of circumstellar discs, the formation of large circumbinary discs ispossible. This can lead to the formation of planets around binary stars to be just as likely as the their formation around single stars. I also observe a dependence of accretion on episodic accretion, independent of separation. I will also present preliminary work on reproducing observed statistics of protostellar binary separations, and what it means for understanding binary formation pathways.

Galaxy clusters are the largest gravitationally bound structures in the Universe. Their formation out of small initial density fluctuations holds important clues to the behaviour of gravity over large distances and long timespans. The standard cosmological paradigm (ΛCDM) makes precise predictions for the frequency of galaxy clusters with different mass, and for how often they interact. We recently showed that these predictions are ruled out at over six standard deviations by the observed properties of El Gordo (MNRAS, 500, 5249). Such a massive pair of galaxy clusters should not have formed so early in the universe's history, as demonstrated using two statistical analysis methods focusing on how many objects similar to El Gordo are expected in the surveyed region. We also considered the main alternative to ΛCDM, which is called Milgromian dynamics (MOND). The main assumption of MOND is that once the gravity from a point mass falls below some threshold a_0, it then declines only inversely with distance instead of continuing to follow the inverse square law. In this way, MOND can explain the unexpectedly fast rotation curves of galaxies. On larger scales, MOND would significantly enhance structure formation and thereby explain El Gordo, as demonstrated using a previous cosmological MOND simulation. The lack of similarly extreme objects to El Gordo in the low-redshift Universe might indicate that we are in a large void. There is actually quite strong evidence for such a void, which would also naturally explain the unexpectedly fast local expansion of the Universe (MNRAS, 499, 2845).

Paper: https://arxiv.org/pdf/2012.02442.pdf

Besides the Galactic Center, GRAVITY’s dual-feed mode also enables observations of faint companions to nearby stars, such as exoplanets and brown dwarfs. By combining the light of four telescopes, precise astrometry and high-quality spectra of these companions can be obtained. In this talk, I will first illustrate the setup of exoplanet observations with GRAVITY. Then, I will show that GRAVITY’s spectrographs are affected by correlated errors and how they can be mitigated in order to increase the achievable contrast. In the second half of the talk, I will focus on the reddest known sub-stellar companion HD 206893 B and what we can learn about its orbit and atmosphere from our GRAVITY data. Due to its extremely red color, this specific object represents a benchmark case for atmospheric models and highlights the challenges in revealing the nature of a companion (exoplanet or brown dwarf) in direct imaging.

Understanding the magnetic field strength and morphology of astrophysical regions is of great importance in understanding their dynamics. There exist a number of methods astronomers can employ to trace magnetic field structures, and each have their own limitations. A promising technique to trace the magnetic field morphology around evolved stars, or on the smallest scales of (high-mass) star forming regions, is (sub-)millimeter spectral line polarization observations. Line (linear) polarization can either arise in association with maser radiative transfer, or alternatively, molecular lines polarize through the Goldreich-Kylafis effect. In both cases, the polarization angle traces the magnetic field with a 90-degree ambiguity. In order to remove this ambiguity, and to estimate the observational viability of particular line polarization measurements, polarized line radiative transfer needs to be employed.

In this talk, I present

(i) polarized radiative transfer tools that quantify the polarization of maser radiation,

(ii) a three-dimensional polarized line radiative transfer tool: PORTAL. PORTAL simulates the emergence of thermal molecular line polarization in astrophysical objects of arbitrary geometry and magnetic field morphology,

(iii) A novel polarization mechanism: collisional polarization. Which provides the possibility of directly detecting ambipolar diffusion in disks through the polarization of molecular ions,

and I will discuss observations of molecular line polarization around evolved stars andon the smallest scales of (high-mass) star forming regions.

Merging between galaxy clusters are the most energetic events in the Universe. Part of the energy released during these events is channeled into shocks and turbulence that accelerate particles in the Intra Cluster Medium (ICM) and produce diffuse cluster-scale radio emission. These sources have been studied for decades using observations at GHz-frequency, however, under many aspects, their origin remains unclear. Given the steepness of the spectrum of these sources, low frequency observations were the crucial, albeit missing, piece of the puzzle to understand these non-thermal phenomena. In this respect, the Low Frequency Array (LOFAR), recently opened a new frequency window (10-240 MHz) in the radio sky, which is the most promising window in this field. On one hand, this is leading to the discovery of new types of diffuse sources and physical interactions in the ICM, such as gently re-energised tails and even beyond the cluster-scale, such as bridges connecting pairs of galaxy clusters. On the other hand, thanks to the superior survey speed and sensitivity of LOFAR, we now have the possibility to analyse large samples of galaxy clusters, even in mass and redshift ranges that were previously inaccessible. In this talk, I will review some of the most important results that have been achieved in the past few years with LOFAR observations of galaxy clusters and I will discuss the ongoing and future work on the largest samples of clusters observed at low frequency.

I will present ALMA 3 mm observations with a resolution of 6.5 au that confirm one of the most well-known Class 0 systems as a triple, with the closest pair (Source A) currently separated by 54 au. Both disks traced by the dust towards source A are compact (<12 au), and significantly misaligned with respect to the extended circumbinary structure. Continuum substructures are also revealed surrounding the two disks, coinciding with the location at which emission from COMs (HNCO, NH2CHO, t-HCOOH) appears enhanced. I will show the gas kinematics resolved down to 13 au scales, from which masses for the protostars within A are estimated and found sufficient for the pair to be bound. The relative motion of the protostars within A, revealed using 30 years of VLA observations, indicates an orbital trajectory.  The combined protostellar+compact disk mass derived from the possible orbital solutions is consistent with the masses derived from gas motion. The ALMA high-resolution data provides a unique insight into the structure, gas and stellar kinematics of a deeply embedded multiple system. 

Long-baseline optical interferometry, e.g. with the VLTI, enables observations with unprecedented angular resolution. In this talk, I will explain how interferometric techniques can be applied to a single telescope in order to obtain well-calibrated observables and achieve the highest possible angular resolutions of down to ~0.5 λ/D. I will discuss an observational technique called aperture masking interferometry (which we have seen in Peter Tuthill’s KES in 2019) and derive its advancement called kernel phase interferometry. After a brief comparison of these two techniques, I will illustrate how stars and companions look like through the eyes of an interferometer. Finally, I will show how kernel phase interferometry can be used to search for brown dwarf and planetary-mass companions in the nearest star-forming regions.

Over the past decade comprehensive and systematic studies of star formation and the gas contents of galaxies during the epochs that are associated with the peak (z~1-3), and subsequent winding down (z<1) of star formation have enabled us to illustrate the important role that cold gas plays in the assembly of galaxies across cosmic time. These studies show that star forming galaxies contained significantly more molecular gas at earlier cosmic epochs than at the present time. Global rates of galaxy gas accretion, which vary with cosmological expansion, primarily drive this increase in cold gas and star formation rates in the dominant main sequence galaxy population. Studies also show that the molecular gas depletion time depends mainly on redshift or Hubble time, and at a given z, on the vertical location of a galaxy relative to the “star formation main sequence”. In this talk, I will discuss various strategies and methods used to determine the evolution of cold gas contents, and discuss the latest gas scaling relations with redshift, star formation and stellar mass. I will also discuss howsimple gas regulator models successfully predict the combined evolution of molecular gas fractions, star formation rates, galactic winds, and gas phase metallicities.

On the duration of the embedded phase of star formation: https://arxiv.org/pdf/2012.00019.pdf

The variability of AGN is stochastic in its nature (e.g. Vaughan et al. 2003). It is well modelled as local fluctuations in the accretion flow propagating inwards, where most of the energy is dissipated but the flow contains the memory of all the local time-scales. However, apart from this regular, low-level stochastic variability, some AGN occasionally show exceptionally large changes in the luminosity, spectral shape and/or X-ray absorption. The most notable are the changes of the spectral type, when the source classified as a Seyfert 1 becomes a Seyfert 2 galaxy, or vice versa.Thus a name was coined of 'Changing-Look AGN' (CL AGN).

Only a few cases were recorded in the past (e.g. NGC 5548, Peterson et al. 1987). Recently the number of new CL AGN is growing rapidly (MacLeod et al. 2019), so the phenomenon is apparently not so rare as previously thought. The origin of this phenomenon is still unknown, but for most of the sources there are strong arguments in favor of the intrinsic changes (e.g., Kynoch et al. 2019, Hutsemekers et al. 2019). Understanding the nature of such rapid changes is a challenge to the models of accretion flow onto the black hole. The time-scales are much shorter than the usual viscous time-scales in the accretion disks (of order of hundreds of years, or longer, depending on the black hole mass and the Eddington ratio). There are no convincing models of this phenomena, although some mechanisms are already proposed (e.g. Ross et al. 2018, Sniegowska et al. 2020).

The results of the Gaia astrometric mission have ushered in a new era of "precision Galactic dynamics". Using this new phase-space map of Galactic stars with unprecedented volume, we are beginning to obtain new insights into the dark matter distribution in our Galaxy as well as its formation history. Thanks to significant advances on the computational front, meanwhile, we can now compare these insights directly with, and test our modeling strategies on, simulations of Milky-Way-mass galaxies where the influence of baryons and the cosmological context on the dark matter structure are realistically taken into account. I will demonstrate how this convergence of new data and better models can improve our understanding of the Milky Way's dark matter distribution, leading to better constraints on the nature of dark matter.

In recent years, ALMA has allowed for probing the the Sunyaev-Zeldovich (SZ) effect at unprecedented sensitivity and angular resolution, thus opening a millimetre-wave window - complementary to X-ray observations - on the evolution of galaxy clusters and the physics of the intracluster medium. I will present the recent results from a high-resolution multi-wavelength study of one of the most massive clusters ever observed at a redshift larger than 1, SPT-CL J2106-5844. The unique capabilities of ALMA+ACA allow one to resolve the bimodal structure of the ICM, corresponding to the peaks in the mass distribution but difficult to identify in the X-ray data alone. The radio observations by ASKAP and ATCA further revealed the presence of an extended complex of radio sources, of which part is associated with strong star formation activity within the cooling cluster core. All this demonstrates how the combination of SZ information at high angular resolution with data spanning the whole electromagnetic spectrum can be pivotal in the characterization of dynamical and thermodynamical properties of galaxy clusters.

Planet formation is expected to be enhanced around snowlines in protoplanetary disks, in particular around the water snowline. However, the close proximity of the water snowline to the host star and water in the Earth's atmosphere makes a direct detection of the water snowline in protoplanetary disks challenging. Following earlier work on protostellar envelopes, the aim of this research is to investigate the validity of HCO+ and H13CO+, as tracers of the water snowline in protoplanetary disks, as HCO+ is destroyed by gas-phase water. Two small chemical networks are used to predict the HCO+ abundance in a typical Herbig Ae disk. Subsequently, the corresponding emission profiles are modelled for H13CO+ and HCO+ J=2-1, which provides the best balance between brightness and optical depth effects of the continuum emission. The HCO+ abundance jumps by two orders of magnitude just outside the water snowline at 4.5 AU. We find that the emission of H13CO+ and HCO+ is ring-shaped due to three effects: destruction of HCO+ by gas-phase water, continuum optical depth, and molecular excitation effects. The presence of gas-phase water causes an additional drop of only ~13%  and 24% in the center of the disk, for H13CO+ and HCO+, respectively. For the much more luminous outbursting source V883 Ori, our models predict that the effect of dust and excitation are not limiting if the snowline is located outside ~40 AU. Our analysis of ALMA observations of HCO+ J=3-2 is consistent with the water snowline located around 100 AU and thus the snowline is unrelated to the abrupt change in the continuum observed at 42 AU. The HCO+ abundance drops steeply around the water snowline, but dust and excitation can conceal the drop in HCO+ emission due to the water snowline. Therefore, locating the water snowline with HCO+ in Herbig disks is very difficult, but it is possible for outbursting sources like V883 Ori.

Since the discovery of the first extrasolar planet orbiting a Solar-like star in 1995, exoplanet science has been evolving into a highly dynamic field of modern astrophysics. Today we know more than 4000 exoplanets and thanks to ongoing efforts from the ground and from space this number keeps continuously increasing. While most of the planets have been discovered via indirect techniques, such as the radial velocity and transit techniques, the direct detection of (small, terrestrial) exoplanets will be required in order to test hypotheses concerning exoplanet habitability and the possible existence of bio-signatures in a statistically relevant sample of objects. In this talk, I will briefly review the current state of high-contrast exoplanet imaging today, discuss the challenges that need to be overcome in order to directly take a picture or a spectrum of an exoplanet, and present a way forward, how we will eventually be able to search for indications of biological activity in exoplanet atmospheres around nearby stars.

In this informal discussion, ESO students and fellows will present the Nobel Prizes awarded in 2020.
There will be a short presentation on each prize, focusing on the main results which led to it.
The list of presentations is:

Medicine
Harvey J. Alter, Michael Houghton and Charles M. Rice
Presentation by Avinash Chaturvedi

Chemistry
Emmanuelle Charpentier and Jennifer A. Doudna
Presentation by Rosita Kokotanekova

Literature
Louise Glück
Presentation by Dominika Itrich

Peace
World Food Program
Presentation by Teresa Paneque Carreno

Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel
Paul R. Milgrom and Robert B. Wilson,
Presentation by Samuel Ruthven Ward

Surveys of bright sub-millimetre sources with ALMA have provided the first unbiased view of intense star formation at high redshift and have allowed for detailed studies of their structures and star formation triggers. I will present a detailed analysis of high resolution (0.18") 870um continuum maps of ~150 sub-mm galaxies (SMGs) selected from the ALMA-SCUBA-2 UDS survey. These observations resolve the dust which traces ongoing star formation within the interstellar medium of these galaxies, and typically have infrared light profiles consistent with exponential discs. The profiles also reveal an axis ratio distribution best described by triaxial shapes. This suggests that the sub-millimetre emission is tracing bars, which are funnelling cold gas from the outer part of the galaxies into the centres. Previous studies have suggested that SMGs may be the high-redshift analogs to local merger-dominated ultra-luminous infrared galaxies (ULIRGs). However, these results and other recent studies, suggest that SMGs instead have disc morphologies. This means that ALMA - once again - is revealing important differences between high-redshift SMGs and local ULIRGs.