The interactions between forming stars and their environment shapes the natal birth cloud, the efficiency at which stars form and the stellar initial mass function. Commonly, signatures of stellar feedback are identified “by eye” However, this approach is challenging, time-consuming and subjective. In this talk I will show how a combination of state-of-the-art numerical simulations together with machine learning can be harnessed to identify and study features created by stellar winds and outflows. I will present a convolutional neural network method, 3D Convolutional Approach to Structure Identification (CASI-3D), which can be efficiently and accurately applied to find connected structures in density and spectral data cubes. I will discuss the implications for estimating the distribution, properties and impact of stellar feedback in molecular clouds. Meanwhile, unsupervised machine learning approaches are powerful tools for identifying patterns in high-dimensional data. I will briefly discuss results using unsupervised methods to study the evolution of gas in molecular clouds and identify an evolutionary sequence for dense cores.

The interaction of massive stars with their environments regulates the evolution of galaxies. Mechanical and radiative energy input by massive stars stir up and heat the gas and control cloud and intercloud phases of the interstellar medium. Stellar feedback also governs the star formation efficiency of molecular clouds. On the one hand, stellar feedback can lead to a shredding of the nascent molecular cloud within a few cloud free-fall times thereby halting star formation. On the other hand, massive stars can also provide positive feedback to star formation as gravity can more easily overwhelm cloud-supporting forces in swept-up compressed shells. Moreover, stellar feedback is an important source of turbulence in the interstellar medium.

The combination of sensitive THz heterodyne receiver arrays with a nimble telescope on SOFIA enables large scale, [CII] 158μm surveys of regions of massive star formation. This line is the main cooling line of neutral gas in the interstellar medium and therefore a key diagnostic of interstellar gas energy balance. In addition, the high spectral resolution inherent to heterodyne techniques allows a detailed study of the kinematics of photodissociation regions, which separate ionized from molecular gas. I will present results of the [CII] 158μm square degree Orion Survey and the SOFIA/upGREAT FEEDBACK Legacy Program, their analysis and implications for the interaction of massive stars with their environment and their role in the evolution of galaxies.

To make substantial progress in our understanding of the shape, internal compositional structure (i.e., density) and surface topography of large main belt asteroids, we have been carrying out an imaging survey with VLT/SPHERE via an ESO Large program (PI: P. Vernazza; ID: 199.C-0074) of a statistically significant fraction of all D>100 km main-belt asteroids (~40 out of ~200 asteroids; our survey covers the major compositional classes).

I will present an overview of the results obtained after 2.5 years of observations. So far, every target has challenged current knowledge, with for instance the linkage between an observed impact crater and a small collisional family (Vernazza et al. 2018), the first high angular resolution images of Psyche, target of a forthcoming NASA discovery mission, implying a density compatible with that of stony-iron meteorites (Viikinkoski et al. 2018), the bluffing view of asteroid (4) Vesta (Fetick et al. 2019), the homogeneous internal structure of CM-like asteroid (41) Daphne (Carry et al. 2019), the heavily cratered surface of Pallas (Marsset et al., Nature Astronomy in press), the basin-free spherical shape of Hygiea while it suffered a giant impact that is at the origin of one of the largest asteroid families (Vernazza et al. 2019), and the nearly hydrostatic equilibrium shape of Interamnia (Hanus et al., A&A in press), to name a few.

I will also present a review of the techniques employed to reach our science objectives (3D reconstruction & deconvolution of the reduced images).  In particular, the 3D reconstruction algorithm MPCD (Jorda et al. 2016) developed in the framework of the Rosetta space mission has been successfully adapted to our VLT/SPHERE data whereas our deconvolution algorithm has successfully passed the test in the case of (4) Vesta (Fetick et al. 2019) although some residual artifacts imply that the technique can still be improved.

It is now well established that chemistry in our Milky Way as well as in external galaxies is rich and complex. In this talk, I will show how molecules from our own Galaxy, as well as other galaxies, play a key role in the formation and shaping of such galaxies. By using examples from different regions of space, from interstellar and star-forming gas in the Milky Way, to extragalactic star-forming regions I will demonstrate how important molecules are for our understanding of star and galaxy formation. Finally, I will present a new approach for the interpretation of molecules using Bayesian and Machine Learning techniques.

GRAVITY! What a wonderful instrument! It was built to have the sensitivity to observe the galactic center, and since then, unrelated scientific results are being announced: gravitational lensing, X-ray binaries, AGNs, … Then came the first detection of an exoplanet by optical interferometry. During this talk, I will show why this first detection was so transformative, and how it will impact the domain past the age of the ELT.

The environments in which young stars form show a rich and varied chemistry. In fact, most of the molecules detected in the interstellar medium to date have first been found in these regions. These molecules range all the way from simple di- and tri-atomic species to complex organic molecules, some of them with ten atoms or more, that can be considered the starting points for eventual prebiotic chemistry. Recently the Atacama Large Millimeter/submillimeter Array (ALMA) has opened new possibilities for studying this complex chemistry. In this talk I will present some of our recent ALMA results concerning the chemistry taking place in star forming regions. I will discuss the implications of these results on the formation of complex organic molecules around young protostars and the link between the birth environments of these protostars, the conditions in their protoplanetary disks and eventually the chemistry in emerging solar systems.

After discussing the importance of the physical processes that are able to remove gas from galaxies, I will describe what are the so-called "jellyfish galaxies" and what we can learn studying them. I will show how integral-field spectroscopy allows us to investigate the rich physics involved and present results regarding the star formation activity, the multi-phase gas content and the possible existence of a connection between gas stripping and AGN activity.

LINK/meeting-id: https://zoom.us/my/jac1604

The Hubble constant remains one of the most important parameters in the cosmological model, setting the size and age scales of the Universe. Present uncertainties in the cosmological model including the nature of dark energy, the properties of neutrinos and the scale of departures from flat geometry can be constrained by measurements of the Hubble constant made to higher precision than was possible with the first generations of Hubble Telescope instruments. A streamlined distance ladder constructed from infrared observations of Cepheids and type Ia supernovae with ruthless attention paid to systematics now provide <2% precision and offer the means to do much better. By steadily improving the precision and accuracy of the Hubble constant, we now see evidence for significant deviations from the standard model, referred to as LambdaCDM, and thus the exciting chance, if true, of discovering new fundamental physics such as exotic dark energy, a new relativistic particle, or a small curvature to name a few possibilities. I will review recent and expected progress.

Zoom link: https://zoom.us/my/jac1604

The Extremely Large Telescope (ELT) is a revolutionary scientific facility that will allow the ESO astronomical community to address many of the most pressing unsolved questions about our Universe. The ELT with its 39-metre primary mirror will be the largest optical/near-IR telescope in the world and will open a huge discovery space.

In this presentation I will provide an overview of the ELT Programme, highlighting the latest status of the telescope and the instrumentation. I will then focus on the key science drivers: from the discovery of extrasolar planets and possibility of life, to the evolution of stars and galaxies, to Cosmology and our understanding of the Universe.

Reconstructing the past of the Milky Way depends on the study of its metal-poor stars, which either have been formed in the Galaxy itself in the first billion years, or have been accreted through mergers of satellite galaxies over time. These stars are usually found in what is known as the Milky Way halo, a light — in terms of total mass —  stellar component which is usually seen to contain stars whose kinematics significantly deviates from that of the Galactic disc.

In this talk, I will discuss how it has been possible to use the astrometric and spectroscopic data delivered by Gaia and complementary surveys  to shed light on the past of our Galaxy, through the study of its halo. Besides the discovery of the possible last significant merger experienced by the Milky Way, the use of 6D phase space information and chemical abundances allowed to reconstruct the impact this merger had on the early Milky Way disc, and the time it occurred, as well as to discover that some of the most metal-poor stars in the Galaxy possibly formed in a disc.  This last finding would implyt that the dissipative collapse that led to the formation of the old Galactic disc must have been extremely fast.

The MIGHTEE large survey project is surveying four of the most well-studied extragalactic deep fields, totalling ~20 square degrees to micro-Jy sensitivity at Giga-Hertz frequencies, as well as an ultra-deep image of a single ~1 square degree MeerKAT pointing. The observations will provide radio continuum, spectral line and polarisation information. As such, MIGHTEE, along with the excellent multi-wavelength data already available in these deep fields, will allow a range of science to be achieved. Specifically, MIGHTEE is designed to significantly enhance our understanding of, (i) the evolution of AGN and star-formation activity over cosmic time, as a function of stellar mass and environment, free of dust obscuration; (ii) the evolution of neutral hydrogen in the Universe and how this neutral gas eventually turns into stars after moving through the molecular phase, and how efficiently this can fuel AGN activity; (iii) the properties of cosmic magnetic fields and how they evolve in clusters, filaments and galaxies. MIGHTEE will reach similar depth to the planned SKA all-sky survey, and thus will provide a pilot to the cosmology experiments that will be carried out by the SKA over a much larger survey volume.

In this talk, I will provide an overview of the MIGHTEE project, the current status of observations and some early science results.

Turning the raw data of an instrument into  high-fidelity pictures of the Universe is a central theme in astronomy. Information field theory (IFT) describes probabilistic image reconstruction from incomplete and noisy data exploiting all available information. Astronomical applications of IFT are galactic tomography, gamma- and radio- astronomical imaging, and the analysis of cosmic microwave background data. This talk introduces into the basic ideas of IFT, highlights its astronomical applications, and explains its relation with contemporary artificial intelligence.

Giant molecular clouds (GMCs) are the home of the most extreme conditions and the most dramatic events found in the interstellar medium (ISM). As hosts of the densest, coldest portion of the ISM’s gas, gravitational collapse is inevitable, and leads to the formation of star clusters. These young star clusters, in turn, host massive and luminous stars that profoundly alter — and ultimately destroy — their birth clouds, by a combination of photoevaporation, radiation forces on dust, and strong shocks from winds and supernovae. Because GMCs are porous, the energy injected by massive stars also escapes to power the surrounding ISM. Given the complex array of processes involved, numerical simulations are essential to developing quantitative models of the lives and deaths of star-forming GMCs. In this talk, I will describe results from recent radiation (magneto-) hydrodynamic simulations that have helped us to understand how star-forming GMCs self-regulate, while simultaneously regulating the thermal, ionization, and turbulent states of the distant diffuse ISM.

The Bar and Spiral Structure Legacy (BeSSeL) Survey uses Very Long Baseline Interferometry (VLBI) to provide  trigonometric parallax measurements for O-type stars across the Milky Way.  The Survey is named for Friedrich Bessel, who measured the first stellar parallax using the last telescope built by Muenchen's Joseph Fraunhofer.  I will show Bessel's original data and comment on its accuracy.

There are now about 200 parallaxes measured with VLBI, and these are accurately tracing spiral structure of the Milky Way, the distance to its center, its rotation curve, and the location of the Sun.  We have developed a Bayesian approach to leverage these results to estimate distances to large numbers of sources from surveys based only on Galactic coordinates and velocities.  Using this program we can make a realistic visualization of the Milky Way.

Additionally, our results make strong predictions for the distance of the Hulse-Taylor binary pulsar, assuming its orbital decay from gravitational radiation follows General Relativity, and for the proper motion of Sgr A*, if indeed it is a supermassive black hole.

The message of the Kepler space mission is this: super-Earths abound in the Universe. These are planets ~1--4 Earth radii and ~1--20 Earth masses, composed of solids and gas in proportions of 100:1 by mass. We describe how super-Earths/sub-Neptunes form within circumstellar disks of gas and dust. From basic astrophysical considerations of gas dynamical friction, gravitational scatterings and mergers, and atmospheric accretion by cooling, we infer a planet formation history that occurs largely in-situ, and late in the life of a protoplanetary disk.  We show how theory explains observed occurrence rate trends with orbital period, including the period ratio distribution that exhibits curious excesses near resonances, and can be expanded to accommodate rarer subpopulations such as sub-Saturns (a.k.a. "super-puffs"). Predictions will be highlighted.

Fast radio bursts are flashes of radio waves originating from so-far unidentified sources at cosmological distances. The bursts are luminous, have durations on the order of milliseconds, and occur often throughout the Universe. Some have been observed to repeat, while others have only been observed as "one-off" events. One of the biggest questions of the field is whether this is an astrophysical distinction or an observational bias. In any case over 50 cataclysmic and non-cataclysmic source models have been proposed, suggesting that multiple source populations of FRBs may be possible.

In roughly the first decade after their serendipitous discovery in 2007, progress was hampered by low numbers of detections and the inability to associate an FRB with its host galaxy. This changed dramatically in the last few years, as new telescopes began discovering large numbers of FRBs and achieving the spatial precision needed to associate FRBs to their hosts. In this colloquium I will provide an overview of the status of the field, including recent key discoveries by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), the Australian SKA Pathfinder (ASKAP), and Deep Synoptic Array - 10. I will also discuss a few interesting sources in more detail, including FRB 121102, the first repeating FRB and the first FRB to be localized.

Discovering new physics beyond the Standard Model is the holy grail of modern particle physics. There has been a recent surge of interest in axions and axion-like particles, in part due to the possibility that they may constitute some fraction of the non-baryonic dark matter (coupled with the failure to detect weakly-interacting massive particles), and also due to the fact that they are generically-predicted by String Theories. In this talk, I shall discuss how astrophysical observations provide a multitude of powerful ways to constrain axion-sector physics. I shall particularly highlight how the transparency (or lack thereof) of the magnetized intracluster medium (ICM) to X-rays from embedded luminous AGN can be a powerful probe of axion-like particles. I will present new data from the Chandra X-ray Observatory for the Perseus cluster which allows us to set constraints on the properties of any low-mass axion-like particles that exceed those possible from the next-generation laboratory and ground-based searches. Our limits are already in moderate tension with predictions from String Theory. I shall end by highlighting the power of the Athena X-ray Observatory for future such studies.