Seminars and Colloquia at ESO Garching and on the campus

With the aim of characterizing the role played by magnetic fields in the formation of young protostars, several recent studies have revealed unprecedented features toward high angular resolution ALMA dust polarization observations of Class 0 protostellar cores. Especially, the dust polarization has been found to be enhanced along the irradiated cavity walls of bipolar outflows, but also in region most likely linked with the infalling envelope, in the form of filamentary structure being potential magnetized accretion streamer.  These observations allow us to investigate the physical processes involved in the Radiative Alignment Torques (RATs) acting on dust grains from the core to disk scales. Synthetic observations of non-ideal magneto-hydrodynamic simulations of protostellar cores implementing RATs, show that the ALMA values of grain alignment efficiency lie among those predicted by a perfect alignment of grains, and are significantly higher than the ones obtained with the standard RAT alignment of paramagnetic grains. Ultimately, our results suggest dust alignment mechanism(s) are efficient at producing polarized dust emission in the local conditions typical of Class 0 protostars. However, further study leading to a better characterization of dust grain characteristics, or additional grain alignment mechanisms, will be required to investigate the cause of strong polarized dust emission located in regions of the envelope where alignment conditions are not favorable. A new attempt aiming at a better characterization of the dust grain alignment mechanism(s) occurring in young star forming objects, is to investigate the chemistry going on in those cores, and see if the local physical conditions (irradiation, temperature) can reconcile both molecular line emission and dust polarization observations.

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles discovered in the first eROSITA all-sky survey image. These 'eROSITA bubbles' extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are part of a vast Galaxy-scale structure closely related to features seen in γ-rays (aka Fermi bubbles). Large energy injections from the Galactic centre are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 10^56 erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.

Paper: Thermal damping of Weak Magnetosonic Turbulence in the Interstellar Medium

http://arxiv.org/abs/2011.13879

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

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

Low to intermediate mass stars, as for example the Sun, evolve towards the asymptotic branch of giants (AGBs), showing increased mass loss during their evolution. AGBs are crucial contributors to the chemical enrichment of galaxies because they lose huge amounts of their mass. 

These stars are characterized by:

• large-amplitude variations in radius, brightness, and surface temperature; and

• a high rate of mass loss due to an interaction between pulsation, dust formation, and radiative pressure on the surface.

Their complex dynamics affect measurements and amplify uncertainties on their stellar parameters. Their surfaces are covered by a few large convective cells (with a long life span). These are supported by smaller-scale structures with a shorter duration. The atmosphere above the surface is made up of shock waves, that are produced inside the star and shaped by the top of the convection zone, when these shock waves travel outward. In the presence of light asymmetries, the position of the photocentre does not coincide with the barycentre of the star and changes as the convective pattern changes over time.

The displacement of the photocentre can be explained by numerical simulation, suggesting that the variability related to stellar convection largely explains the Gaia parallax uncertainties. Consequently, parallax variations on Gaia's measurements could be used to extract the fundamental parameters of these stars. With future releases of Gaia, more precise parallax measurements will become available which will hopefully improve these characterisations even further.

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

Material from the cloud core is transported onto the protostar by accretion flows. In multiple protostellar systems, particularly for those with separations larger than disk scales, it is not clear how material is distributed. To find out whether material is preferentially or evenly distributed among the components, the cloud core structure of embedded multiple protostellar systems needs to be characterized. ALMA observations of IRAS 16293 revealed an extended, filament-like structure connected to source A, but not source B. The extended structure is traced in HC3N, HC5N, HNC, H13CO+ and N2H+, but shows no dust continuum counterpart. Analysis of the morphology and physical conditions indicate that the extended structure is a cold gas accretion flow, delivering material  onto source A. In addition, ALMA observations reveal further details about the outflows driven by IRAS16293 A. The implications of these results on material accretion of multiple protostellar systems will be discussed in this talk.

Gaia (E)DR3 was released on 03 December. Join us for an informal chat on the catalogue content, how to use the data for your scientific applications, and a discussion on the main scientific results that were presented.

In the first part of the seminar, I will talk about an object-by-object comparison between the L-Galaxies semi-analytical model and the IllustrisTNG hydrodynamical simulations. I highlight the similarities and differences, focusing on the properties of galaxies in different environments.

In the second part of my talk, I introduce a local background environment (LBE) estimator to quantify environment, locally, for all galaxies within cosmological simulations. I use the time-evolving LBE of galaxies to develop a method to better account for ram-pressure stripping of gas within the Munich semi-analytical model, L-Galaxies. I calibrate the updated model using a Markov Chain Monte Carlo (MCMC) method and observational constraints from the stellar mass function and quenched fraction of galaxies at z < 2. By comparing to data on galaxy properties in different environments from different surveys (e.g. SDSS, HSC), I demonstrate that the updated model significantly improves the agreement with the quenched fractions and star formation rates of galaxies as a function of stellar mass, halocentric distance, and host halo mass. Overall, in the vicinity of massive haloes, the new model produces higher quenched fractions and stronger environmental dependencies, better recovering observed trends with halocentric distance up to several virial radii. By analysing the actual amount of gas stripped from galaxies in the new model, I show that those in the vicinity of massive haloes lose a large fraction of their hot halo gas prior to their infall. This is likely to influence the correlations between galaxies up to tens of megaparsecs.

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

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

If stellar atmospheres, stellar evolution, binaries and/or fully formed (exo)planets are your cup of tea (or of coffee), then please join us for a mix of informal chat and short presentations.

Deep Learning and its conceptual differences to classical machine learning have been largely overlooked in the community. The broad hypothesis motivating our current projects at the ESO AI Lab is that letting the abundant real astrophysical data speak for itself, with minimal supervision and no labels, can reveal interesting patterns which may facilitate discovery of novel physical relationships. This talk is about our first step, where we seek to interpret the representations a deep convolutional neural network chooses to learn, and find correlations in them with current physical understanding. We train an encoder-decoder architecture on the self-supervised auxiliary task of reconstruction to allow it to learn general representations without bias towards any specific task. As a case study, we apply this framework to HARPS, a dataset of ~270000 stellar spectra, each of which comprising ~300000 dimensions. We find that the network clearly assigns specific nodes to estimate (notions of) parameters such as radial velocity and effective temperature without being asked to do so, all in a completely physics-agnostic process. This supports the first part of our hypothesis. Moreover, we find with high confidence that there are ~4 more independently informative dimensions that do not show a direct correlation with our validation parameters, presenting potential room for future studies.

The ESO workshop "Ground-Based Thermal Infrared Astronomy – Past, Present and Future" was held on-line from October 12-16, 2020. Originally planned as a traditional in-person meeting at ESO in Garching during April 2020, it was rescheduled and transformed into a fully on-line event due to the COVID-19 pandemic. With 337 participants from 36 countries the workshop was a resounding success, demonstrating the wide interest of the astronomical community in the science goals and toolkit of ground-based thermal infrared astronomy. In this informal discussion we will report on the organization of the workshop and will present some of the science highlights.

Paper: https://arxiv.org/pdf/2010.15135.pdf

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

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

In the last 10 years or so there have been huge developments with telescopes like ALMA and it is becoming evident that protoplanetary discs are characterised by substructures. Understanding the origin of these substructures is one of the few challenges to shed light on the possible mechanisms involved in planet formation. Among the myriad of observed substructures, asymmetries are definitely the most intriguing and, in particular, the ones originated by misaligned or broken discs. Misalignments within protoplanetary discs are now commonly observed, and features such as shadows in scattered light images are clear signatures of departure from a co-planar geometry. A recent and interesting case is the disc around HD143006. Observations at both optical and millimeter wavelengths show multiple substructures within this disc and are proving to be puzzling to interpret. We present a promising scenario able to explain most of the observed features and possibly making HD143006 a very unique system. 

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

More than one hundred years ago, Albert Einstein published his Theory of General Relativity (GR). One year later, Karl Schwarzschild solved the GR equations for a non-rotating, spherical mass distribution; if this mass is sufciently compact, even light cannot escape from within the so called event horizon, and there is a mass singularity at the center. The theoretical concept of a `black hole' was born, and was rened in the next decades by work of Penrose, Wheeler, Kerr, Hawking and many others. First indirect evidence for the existence of such black holes in our Universe came from observations of compact X-ray binaries and distant luminous quasars. I will discuss the forty year journey, which my colleagues and I have been undertaking to study the mass distribution in the Center of our Milky Way from ever more precise, long term studies of the motions of gas and stars as test particles of the space time. These studies show the existence of a four million solar mass object, which must be a single massive black hole, beyond any reasonable doubt.

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.

Paper: https://arxiv.org/abs/1712.06217

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

Papers:

https://arxiv.org/abs/2009.06593

https://arxiv.org/abs/2010.09761

https://arxiv.org/abs/2010.14305

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

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

If the title looks scary to you then this talk is made for you. The aim is to define all the words the title contains and give you an overview of each concepts and how they interact with one another. The starting point will be the definition of a segmented mirror, why are they needed and what new challenges they introduce in term of optics. The optical alignment of a segmented mirror requires dedicated tools, methods and time. Among the optical alignment operations to be done is the co-phasing (or phasing for short). A definition is given and ways of measuring it is exposed. Finally, the approach of the ELT to co-phasing its own segmented mirror is explained based on the available published information.

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.

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

A large fraction of stars are born in multiple stellar systems and the impact of stellar multiplicity on the evolution of planet-forming discs is still subject of debate. Dynamical interactions are expected to reduce disc sizes, truncating discs and affecting the availability of the building blocks of planets. We recently acquired high-resolution (~0.12-0.15" ~20 au) Band 6 ALMA observations of line and continuum emission in several multiple stellar systems in the Taurus molecular cloud. Here I will present the data and the analysis of the continuum and line emission, which is detected both around the primary and secondary star in the majority of the targets.

The disk radii measured in our sample allow us to constrain the models of tidal truncation, and whether radial drift is more efficient in multiple stellar systems.

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.

UVES, the UV-Visual Echelle Spectrograph, saw the first light on VLT-UT2 in 2000. Over twenty years, this highly efficient, reliable and flexible “workhorse” instrument has contributed data to countless science cases from Solar System to high-redshift objects, from the study of newborn stars to the analysis of the most primordial ones ever detected, formed shortly after the Big Bang. It quickly became the most productive ESO instrument in terms of published papers, a distinction it still holds to this day. For these reasons UVES is one of the two first-generation VLT instruments (together with FORS2) foreseen to remain in operation in the next decade, and it will thus be in need of an upgrade, both to prevent obsolescence of components, and to maintain its competitiveness in a changed scientific and instrumental landscape. In this virtual workshop we intend to celebrate 20 years of great UVES science and envision the future role of the instrument. Ten prominent scientists will resume the history of UVES, outline the scientific highlights of its long career and offer their insights on how to best equip it to help tackle the scientific questions of the next decade. A final discussion session will address the possible future instrumental upgrades, to balance technical constraints with scientific needs, and help to define a set of compelling science cases.

Astronomy is a very “open” science by nature — sharing (pr-)eprints, data, and code has a long tradition among astronomers. This is shown by the community’s adoption of platforms like arXiv/astro-ph, Github, and the Astrophysics Source Code Library. Do we actually need “official” open access regulations in astronomy if the community embraces the concept of openness so well anyway? Why is this topic relevant for astronomers?

During the week 19 to 25 October 2020, this year's International Open Access Week takes place. In this informal discussion, we will explain recent developments in open access publishing and explore areas that are still missing on our way to an open science community. In addition, we would like to hear from you what you consider essential in an OA journal.

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

Comets are among the most intriguing objects in the Solar System. Traditionally, they were considered to be well-preserved planetesimals that have remained unchanged for billions of years in the outer Solar System and have therefore retained key evidence from the epoch of planet formation. Nevertheless, we now know that Jupiter-family comets (JFCs) have had a rich dynamical history which has taken them from planetesimals in the protoplanetary disk, through long residences as Trans-Neptunian objects (TNOs), followed by a migration through the Centaur region between Jupiter and Neptune to become active or dormant comets making regular passes through the inner solar system. Since comet evolution is very closely related to the environment surrounding them, tracing the changes comets have experienced since formation is key for understanding the conditions in the outer Solar system throughout its history.

In the beginning of this talk, I will introduce the current understanding of the outer Solar System formation and evolution, emphasizing the latest progress in this field driven largely by the Rosetta and New Horizons space missions. I will then proceed to highlight the key role of telescope observations in addressing some of the remaining questions. I will discuss our most recent results on comet and TNOs photometry, as well as our efforts to design space missions that will address the missing knowledge in the coming decades.

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.

Paper: https://arxiv.org/pdf/2009.08740.pdf

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

The interaction between ice and gas in the Universe is an elusive relationship spanning from the formation of simple molecules to the production of building blocks of planetary systems. There are many unanswered questions about the ice-gas interplay in stellar nurseries, e.g., what are the exact chemical and physical processes releasing solid-state molecules into the gas-phase. Such desorption mechanisms are of utmost importance to comprehend some critical aspects of star- and planet- formation. Besides enhancing the chemical complexity in the gas-phase, the position in circumstellar disks at which they occur (i.e., snow-lines), influences the formation and evolution of planets. In this talk I will introduce a way to address the above questions from an observational perspective: combining solid-state (ice) and gas-phase observations of molecular tracers towards the same region. Hence, probing solid- and gas-phase chemistries to a greater extent than by ice or gas observations alone. I will present the results of such combination for the SVS 4 cluster in Serpens Main and for the multiple protostellar system IRAS 05417+0907 in B35A. No straightforward trend is found between ice and gas abundances towards Serpens SVS 4, likely due to its complex morphology. In contrast, an anti-correlation is observed between gaseous molecules and their solid counterparts towards IRAS 05417+0907. Linking gas and ice maps will serve as a pathfinder for future JWST and ALMA observations that will provide high sensitivity ice- and gas-maps of complex organics. The combination of ice and gas abundances will be an indispensable tool to constrain the routes leading to chemical complexity during the earliest stages of star-formation.

Live and Zoom Talk.

White dwarf stars are a well-established tool for studying Galactic stellar populations. Two white dwarfs in a tight orbit forming a double white dwarf (DWD) binary offer us an additional messenger - gravitational waves - for exploring the Milky Way and its immediate surroundings.

Gravitational waves produced by DWDs can be detected by the future Laser Interferometer Space Antenna (LISA). I will discuss what we will learn about our Galaxy from the LISA sample of DWDs. In particular, I will demonstrate how well the density distribution of DWDs constrains scale parameters of the Milky Way's bulge, disc and central bar. Finally, I will show that massive Galactic satellites can be seen on gravitational wave sky and I will present which of their properties we will be able to investigate with LISA.

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

For a radio interferometer like ALMA, the path from the antennas to science data weaves through an interconnected system of many synchronised instruments, operating in optical, analogue and digital electronic domains, distributed between the antennas and a central location. In this lecture I will cover some of the important principles of a heterodyne radio interferometer, and take a tour through the ALMA instrument system from antennas to archived data. As you will have seen from the science results, ALMA has been a game changer, transforming mm/sub-mm observations by an order of magnitude or more in resolution, sensitivity and image fidelity. Yet this is achieved using technologies which were state of the art a decade or more ago, and built to a tight construction deadline. ALMA now has a vision for a major instrument upgrade over the next decade: the ALMA2030 roadmap. I will conclude the lecture by discussing how the roadmap is being translated into ambitious but hopefully achievable specifications, and how this may be implemented based on current technology development in key areas.

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.

Papers:

• Chronology of Episodic Accretion in Protostars - An ALMA Survey of the CO and H2O Snowlines: https://ui.adsabs.harvard.edu/abs/2019ApJ...884..149H/abstract
• ALMA Observations of the Protostellar Disk around the VeLLO IRAS 16253-2429: https://ui.adsabs.harvard.edu/abs/2019ApJ...871..100H/abstract

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

In recent years a wealth of ground and space observations has provided new constraints on the role of cosmic rays in various astrophysical environments. Cosmic rays are involved in several processes related to Galactic star formation at different spatial and time scales. They trigger the complex chemistry observed in molecular clouds, in particular they determine the ionisation fraction that regulates the degree of coupling between gas and magnetic field. The latter, in turn, controls the cloud collapse and the formation of circumstellar discs. Cosmic rays also underlie the basic processes for dust grain charge and coalescence, explain energetic phenomena in protostars such as synchrotron emission in jets, determine the atomic hydrogen fraction in dark clouds, affect the chemical composition of planetary atmospheres, and much more. In my talk I will present the most recent results on cosmic-ray physics and chemistry in star-forming regions obtained by analytical and numerical models supplemented by dedicated observations. 

Agenda

~30min talk

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

~ 30min Q & A session

Paper: Protostellar collapse: regulation of the angular momentum and onset of an ionic precursor

https://arxiv.org/pdf/2009.01268.pdf

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

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

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

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

System engineering (SE), a relatively recently developed domain of knowledge, has even more recently become an integral part of ground-based astronomy projects. More so now that we are building ginormous telescopes and their instruments. ESO itself includes a SE Department in its own organigram since (only) 2014.

Like the name suggests, SE is a field of engineering devoted to management of multidisciplinary projects, or systems, where all components must be made to work together – possibly flawlessly and, in astronomy, for typical lifetimes of 20+ years. If you ask 10 people - any 10 people, at ESO or outside - “what is System Engineering?” you will probably receive 10++ different answers. In this talk, I will propose my own view on it. It evolved in the past 25 years during which I slowly transformed from astronomer to system engineer (did I?). Spoiler alert: my definition is that “SE is just about problem solving”.  A deceptively simple and enticing definition, it’s clearly a trap! Ultimately, in my 35 minutes, I hope to convince the youngest among you that it may be a viable career choice for an astronomer, and I will shamelessly give you a rosy glimpse into the fun parts, like requirement analysis, inventive problem solving or trade-off studies.  For the rest of the story, you will have to invite me again!

For an overview and schedule of past and future lectures: http://www.eso.org/~rvanderb/KES/kes.html

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.

Link: https://us02web.zoom.us/j/99932447653?pwd=STI3dy9uNkgzdjhjUElzQi9EcmR6Zz09

Meeting-ID: 999 3244 7653

Kenncode: 602136

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

Dense cores are the places where stars are formed within the supersonic Molecular Clouds. These dense regions (n~10^5 cc) are cold (T~10 K) and display subsonic levels of turbulence (Mach ~ 0.5), and represent the initial conditions for both star and disk formation. However, the influence of the parental core properties on the disk formation process is still not well constrained, and it is therefore crucial to study dense cores with interferometers to better understand the dense core and disk connection. We present NOEMA observations of a Class 0 object, which has been suggested to present a disk under gravitational instability (GI) (asymmetrical features in ALMA high resolution dust continuum emission). Our new data reveal a previously unseen large scale (~10,000 au) streamer of fresh gas from the surrounding dense core down to the disk scales. This streamer is perpendicular to the outflow, and it contains material with subsonic levels of turbulence, and therefore unperturbed by the outflow. We model the position and velocities using a free-falling streamline, and we estimate an infall rate comparable to the accretion rate onto the protostar. This clearly shows that accretion via streamer can be have an important role in the disk formation. Moreover, these results show that previously observed disk asymmetries could also be driven by large scale asymmetric flows instead of GI. This result shows the power and importance of studying dense cores with interferometers to provide a complete and proper picture of star and disk formation.

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.

Astronomers offer a unique and important perspective that can help people understand the causes, consequences, and solutions for climate change.  Through the classes we teach and our public outreach we reach large numbers of people.  But we need to recognize that climate change is different than the other topics we teach.  Teaching and communicating climate change is challenging because it spans a wide range of subject areas, from physics to psychology.  It is now clear that understanding the science is not enough.  People largely made decisions about climate change based upon their values and identity.  They therefore need to understand how climate change affects things they care about.

We also need to think about how we do our work.  To avoid the worst consequences of climate change, research indicates that humanity must reduce carbon emissions 50% by 2030, and nearly 100% by 2050.  While a small field, astronomy nonetheless has a significant carbon footprint.  Historically we have relied heavily on travel to do our work.  Fortunately there are many ways in which we can reduce our carbon emissions while actually improving our profession.  We have already seen how remote and queue observing improves the science we do, from conducting observations under appropriate sky conditions to enabling time-sensitive science.  Remote participation online is also becoming more common.  While there will always be value in "face to face" engagement, virtual meetings offer the opportunity for more inclusive and equitable participation.  This is particularly true for those with constraints that restrict travel; e.g., small budgets as well as work and family obligations.  By reducing our footprint we send an important message to the world about the seriousness of the problem.  But if done properly we can also use this as an opportunity to improve our profession.

In my talk I will briefly describe effective methods for talking about climate change with our students and the public.  I will also outline ways in which our profession can reduce our carbon footprint.  I will describe strategies being considered by the American Astronomical Society to meet that goal.

Paper: https://arxiv.org/pdf/2007.06050.pdf

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

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

Article:https://arxiv.org/abs/2008.00228

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

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

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

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

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

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

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

With the discovery of exoplanets, theories of planet formation, structure and evolution (planetology) have to simultaneously explain observations with a huge dynamic range: from exquisitely detailed observations of the atmosphere and structure of planets and minor bodies in our Solar System, to population-wide properties of thousands of exoplanets. For exoplanet observers, the challenge is to present the community with a set of observations that can push our understanding of planet formation further, despite the limited information and limited precision that we can access in exoplanets. I propose to discuss the current contribution of exoplanet sciences to planetology through the simplest measurable quantities (radius and mass), and a possible future avenue to increase that contribution through detailed observations of metals in the atmospheres of ultra-hot Jupiters (T_eq >~ 2200 K), the hottest gaseous giants known.

In particular, I will present the first detection of an atomic species in the emission spectrum of an exoplanet (KELT-9b) realized in a single night of observations with the optical HARPS-N spectrograph, mounted on a 4-meter class telescope (Telescopio Nazionale Galileo). Our detection shows: (1) the unambiguous presence of a thermal inversion in the atmosphere of the planet, constraining its atmospheric structure (2) that, given sufficient precision, it is possible to measure the abundance of metals in a sub-class of exoplanets, the ultra-hot Jupiters. This is a crucial step towards establishing a new set of observational tests of planet formation and evolution theories. In the near future, our technique will be extended to cooler exoplanets. In the era of EELTs and JWST, this kind of measurements could ultimately open a new window on exoplanet formation and evolution.

Paper: https://arxiv.org/pdf/2007.07254.pdf

With more than 4000 confirmed exoplanets, evidently, planet formation is common. There is also mounting evidence from observations and meteorites that planet formation starts very early. How do we then form and grow planets frequently and quickly enough to match this evidence? One popular paradigm is pebble accretion. "Pebbles" are mm-to-cm sized dust particles which are abundant in protoplanetary disks, but are not necessarily well-coupled to the disk gas. It is because of this property that pebbles can drift relative to the disk gas and are prime targets for accretion onto young planets. I will present simulations of pebble accretion onto "rocky" planetary embryos (i.e. on the order of an Earth mass) that resolved the disk scale height and the atmosphere of the embryo, but importantly also followed the pebbles over time. These first-of-their-kind simulations reinforced the efficiency and robustness of pebble accretion, even when a convective atmosphere is considered. Indeed, we should perhaps discuss if pebble accretion in its purest form is too efficient relative to our current understanding of how planets grow.

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

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

In this talk I will introduce white dwarfs and discuss the mass distribution of such fascinating objects. We will begin with the first spectroscopic surveys, including the SDSS, and see how our understanding has been improved with the outcome of Gaia.

Paper: http://arxiv.org/abs/2007.07149

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

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

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

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.

The EAS 2020 meeting was forced to move online this year. I'll discuss how they decided to go about it and how this worked out, for attendees, session organisers and virtual exhibitors. What worked well and should be kept in post-covid times and what didn't?

Papers:

https://arxiv.org/pdf/2006.09741.pdf
https://arxiv.org/pdf/2006.03362.pdf

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

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

The chemical composition of planetary atmospheres has long thought to store information regarding where and when a planet accretes its material. Predicting this chemical composition theoretically is a crucial step in linking observational studies to the underlying physics that govern planet formation. Here I will present a synthetic population of warm Jupiters (semi-major axis between 0.5-4 AU) extracted from a planetesimal formation population synthesis model. We compute the astrochemical evolution of the protoplanetary disks that produce our planets to predict the carbon-to-oxygen (C/O) and nitrogen-to-oxygen (N/O) ratio of the planetary atmospheres. The population of synthetic warm Jupiters follow the empirically-derived mass-metallicity relation found for our solar system (higher mass planets have lower metallicity), with some scatter driven by planets forming around super-solar metallicity stars. Jupiter-analogs are planets who's mass and orbital radius coincide with Jupiter, if Saturn had not existed (thereby eliminating the Grand Tack model). Comparing our Jupiter-analogs to Jupiter's elemental ratios shows that its evolution is inconsistent with our formation model - suggesting its formation is more consistent with a pebble accretion or hybrid model. Finally, I will outline the details of carbon refractory erosion as it pertains to our model and how changing the carbon erosion front impacts the chemical properties of our population.

We recently organized the e-conference entitled "Assessing uncertainties in Hubble's constant across the Universe", or #H02020, which took place from 22 to 26 June 2020, daily from 12:50 - 15:10 UTC.

Originally planned as an in-person conference to be held at ESO HQ in Garching, #H02020 was moved to the virtual domain in response to the COVID-19 pandemic that led to strict worldwide travel restrictions and a severe reduction in the number of conferences held this early Summer.
With no blueprints for implementation, we decided to risk the experiment of converting a fully planned conference to a live online event spanning 18 time zones using existing infrastructures and free versions of online tools and platforms.

In this informal discussion, I will present how we went about implementing this e-conference, how it was received, and what we have learned in the process.

Given the very positive response received from the community, we hope that others will build and improve upon our setup in order to make e-conferencing an effective, inclusive, and climate-friendly alternative to in-person meetings.

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

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

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.

I will give an overview of the fascinating nebulae around one of the closest known symbiotic star R Aquarii.

Among other observational facilities, during the last 40 years, ESO telescopes and researchers, have played a crucial role in understanding the nature of this unique system. 

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

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

Disk ionisation is key in understanding how the magneto-rotational instability (MRI) operates to drive the turbulence in protoplanetary disks. In particular, ionisation drives the so-called “dead zones”.

Previous gas/dust evolution models have shown that dust particles can be efficiently trapped at the dead zone outer edge. Thus, it is a promising mechanism to explain some of the current ALMA observations of protoplanetary disks. However, most of those previous studies parametrised the Shakura-Sunyaev α radial profile, neglecting that it is actually entirely constrained and self-consistently derived from the disk properties and ionisation.

In this talk, I will present a module that allows to obtain a self-consistent α-parameter. Coupling that module to the gas/dust evolution model dustpy, we will have the tools to conduct end-to-end simulations that are crucial to understand how the disk properties and ionisation impact on the turbulence, radial drift, settling and diffusion processes of dust particles. Finally, these end-to-end simulations will improve our understanding of the current interpretation of observations.

We have recently reported on the presence and diffusion of weak magnetic fields among the hot stellar populations in Galactic globular clusters. I will try to summarize the results of our survey that led to the identification of both periodic and periodic photometric variability; a twofold manifestation of the often elusive magnetic activity.

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

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

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

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

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

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.

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

Museums (and similar visitor attractions) have experienced unprecedented economic and social consequences in recent times due to the coronavirus. To better understand the status quo and what might come next, the Network of European Museum Organisations (NEMO) launched a survey to map COVID-19’s impact on the museum sector (mostly in Europe). The results are in and the report analyses and documents a sector that, although it is experiencing financial setbacks, is agile and able to adapt to the new normal.
I will present some of the results from this and other studies, whilst also highlighting the impacts on our ESO Supernova.

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

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

One of the largest quantitative discrepancies in the local Universe is that population-synthesis models predict between 108 and 109 black holes (BHs) in the Milky Way while only about two dozen have been detected.  Most of the detections were made in X-rays caused by mass accretion from a companion star.  Although the census of accreting BHs is incomplete due to strong extinction of the optical flux of the companions, there must be many X-ray-quiet BHs of which only 2 or 3 (not uncontroversial) examples have been found to date.  This Informal Discussion will be about a hierarchical triple system with a BH in the inner binary.  Since the BH is not accreting, it is just very dull.  However, its relative proximity to Earth (~300 pc) suggests that it is only the tip of a (black) iceberg.  The two luminous components will not also undergo supernova (SN) explosions.  The system may nevertheless be a local example of an architecture sometimes invoked for some GW sources.  Orbital parameters may also give hints at the properties of the SN explosion. 
The underlying paper by Rivinius, Baade, Hadrava, Heida, and Klement appeared in A&A, 637, L3:
https://www.aanda.org/articles/aa/abs/2020/05/aa38020-20/aa38020-20.html

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

In this talk I will discuss the role played by quasars in the co-evolution of galaxies and black-holes and whether the diversity of quasar colours is explained solely by the AGN unification model or they represent different evolutionary stages. I will present a systematic study on the radio emission of SDSS quasars at low radio frequencies based on a synergy of the LOFAR deep field surveys and multi-wavelength surveys. Intriguingly, we find a large enhancement of radio detections in red quasars when compared to normal quasars and investigate their multi-wavelength SEDs and radio properties in order to characterise the origin of this difference. Our results, together with those from recent high-frequency radio studies, suggest the differences between red and blue quasars do not simply arise from viewing angle effects, but suggest an evolutionary origin.

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

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

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

This exploratory work studies the perception of professional astronomers about the societal impact of astronomy. Ten semi-structured interviews with astronomers from a range of career and cultural backgrounds have been conducted to gain in-depth insight into their opinion about societal impact and their approach in realising it. The results show that the interviewees are aware of the diversity of impacts that astronomical research has. However, they are mostly active in outreach and only a few activities are incorporated into their jobs to achieve an impact on development. There is little contact with stakeholders in industry, policy or other fields, like development. Besides, a structured approach in their personal outreach is lacking, and assessment is only done informally. Despite the limited sample size of this study, the results indicate that a further change is necessary to engage professional astronomers with topics of development and societal impact to create action on the level of individual researchers.

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

As so often in astronomy, the discovery of the first giant planet in a close orbit around a white dwarf was not the culmination of a carefully crafted master plan, but occurred serendipitously. I will summarise how an initial moment of bewilderment turned into an exciting detective story, and ultimately led to a consistent physical model of the current state, and past evolution of this giant planet. From there, it was only one step further to realise that signatures of giant planets surviving the post-main sequence evolution of their host stars are likely to be common - and will eventually be visible to alien astronomers studying the remains of the solar system.

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

Success in science correlates strongly with international (airplane) travel. This practice is increasingly at odds with the colleagues who study climate. In order to explore mechanisms to decrease professional air travel, we staged a CArbon REduced (CARE) conference. The CARE model is a hybrid virtual/live conference involving peripheral nuclei of attendees. We will use our conference format to address the issues that must be addressed to make CARE conferencing mainstream. One conclusion is that we will need to re-learn conferencing skills.

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

In times of crisis, it may help to look back. Inspired by the discussion at the Science Coffee last week, where the autobiographies of famous astronomers in Annual Reviews were mentioned, I decided to take a look at this peculiar literary genre. I found the reading enlightening, at times funny and at times
enraging. I hope to give you some example of what I mean by that. I have chosen to focus on three stories for you: those of James Gunn, Edwin Salpeter and Vera Rubin. The two old men were picked at random, just because they were mentioned at Science Coffee. Vera Rubin is Vera Rubin, so I am sure you will understand why I chose her.

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

Olivier Hainaut will give a short description of what is a satellite constellation and of why they are useful, then discuss of the current plans by satellite operators (SpaceX, Amazon, Samsung, and many others...). He will show some simulations of the effect on astronomical observations (from naked-eye to ELT), and quantify these effects.

Andrew Williamns will discuss the regulatory situation for these satellite operators, and discuss how the current international treaties could be expanded to protect the night sky.

The ELT telescope is under construction. In this informal discussion we offer a Question and Answer session on the telescope system. Do you have questions about how the primary mirror works, how the segments are made, the shape of the other mirrors, why is M4 deformable, what does M5 do, how many guide probes do we use, what is a phasing station, is the dome really that big, how much does the telescope weigh, how will we point the telescope? Or more?
 

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

The James Webb Space Telescope, also called Webb or JWST, is a large, space-based observatory, optimized for infrared wavelengths, which will complement and extend the discoveries of the Hubble Space Telescope. It launches in 2021.

It will cover longer wavelengths of light than Hubble and will have greatly improved sensitivity. The longer wavelengths enable JWST to look further back in time to see the first galaxies that formed in the early universe, and to peer inside dust clouds where stars and planetary systems are forming today." -- https://jwst.nasa.gov

In light of the upcoming proposal deadline of the first open call for proposals, I will give an overview about the general capabilities of JWST, its instruments and will give a live demonstration of the various tools (visibility calculator, exposure time calculator, astronomer's proposal tool) that are needed to prepare a JWST proposal.

I will also share some tips and tricks and lessons learnt from preparing our successful JWST Early Release Science Program Q3D (http://www.stsci.edu/jwst/observing-programs/approved-ers-programs/program-1335).

NOTE: Due to the current spread of COVID-19 ESO management decided to cancel all meetings with external participation until the end of March. As such this Informal Discussion will go ahead for ESO staff only.

Agenda: https://indico.ph.tum.de/event/4431/

This KES lecture will cover the current status of ESO’s Extremely Large Telescope and of the powerful instrument suite that is being designed and built to meet the science case for the ELT. In addition, I aim to give some insight into how such ambitious programmes, like the ELT, come to life. The challenge of building the instruments is greater than anything the ground-based astronomical community has previously attempted, thanks to the size of the telescope and the drive towards reaching diffraction limited observations. The basic concept and scientific capabilities of the first six instruments that are being developed will be summarised.

Over the last decade,  surveys like the SDSS, DES, KiDS, VHS, AllWISE, The Two Micron All Sky Survey, The Sydney University Molonglo Sky Survey, etc, have provided new insights into the physics of objects on all scales from giants early-type galaxies (ETGs) to faint and compact stellar systems, and at all distances from the structure and dynamics of our own galaxy to high-redshift quasars.  

In this informal discussion,  I will start describing few particular scientific problems that can be solved by means of multi-band colors and magnitudes:  object classification, search for strongly lensed quasars, photometric redshifts calculation, identification of high-z galaxies or extremely red objects, focusing in particular on the first two.

I will demonstrate that a wide wavelength coverage is fundamental in these cases and thus introduce the VISTA EXtension to Auxiliary Surveys (VEXAS) project that aims at building the widest and deepest public optical-to-IR photometric and spectroscopic database in the southern hemisphere.

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

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

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

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

A first step towards understanding planetary formation is the characterisation of the structure and evolution of protoplanetary discs. Although the large scale disc is understood in some detail, much less is known about the inner 5 au in which the main physical processes take place: accretion, ejection, and planetary formation. Even in the nearest sites of star formation, this region cannot be spatially resolved by stand-alone telescopes; only in recent years have optical and infrared interferometers been able to achieve this, and only in the case of the brightest sources.

Without doubt, planets are formed from proto-planetary disks around stars, and about four thousand exoplanets have been discovered until now.  However, proto-planetary disks may not be the only site of forming planets in the universe. Here we propose a novel site for planet formation, namely circumnuclear gas disks around supermassive black holes (SMBHs).   Active galactic nuclei (AGNs) are believed to be surrounded by dense, dusty gas, which obscures the emission from the accretion disks. As a result, there should be a cold dust disk beyond several parsecs from the AGN. Recently we investigated growth history from sub-micron sized icy monomers to km-sized planetesimals in circumnuclear disks around SMBHs, based on recent plausible theories of planetesimal formation around stars. We expect that numerous (> 104 pc-2)  "blanets" = black hole planets whose masses are ~ 10 Earth-mass could be formed around some AGNs.

The most dramatic event in the course of a galaxy’s evolution is when it stops forming stars, or quenches. Besides that galaxies quench by internally-driven mechanisms, they also do so as a strong function of their environment - from sparsely populated voids to the densest galaxy clusters. Thanks to large surveys such as SDSS, we have obtained an increasingly clear picture of the particular role of environment in the quenching of galaxies. While this has led to an empirical model that has been successful in describing the basics of galaxy quenching in the local Universe, this model needs to be revised in the more distant (z>~1) Universe. I will first describe where we currently stand in our understanding of environmentally-driven quenching, and then highlight the challenges we face when confronted with data taken of the distant Universe.

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

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

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

As astronomy enters the regime of precision science, astronomical instruments (and their detectors) are pushed ever closer to their technological limits. The quality and noise performance of detectors has improved over the years to the point that small systematic effects can now dominate the error budgets of astronomical instruments. I will go over some common systematic effects found in astronomical detectors, demonstrate what impacts they could have on various science cases, and give some practical strategies for how you, the astronomer, can get involved in ensuring that detector systematic effects don’t limit the science you want to do.

In the search for astrophysical neutrinos, neutrino telescopes instrument large volumes of clear natural water. Photomultiplier tubes placed along mooring lines detect the Cherenkov light of secondary particles produced in neutrino interactions. This allow us to search for possible neutrino sources in the sky.

To overcome the challenges of deep underwater experiments, we are developing prototype mooring lines in collaboration with Ocean Networks Canada, an initiative of the University of Victoria, which provides the infrastructure for many Oceanographic instruments.

The STRAW mooring lines were deployed in June 2018, and provide continuous monitoring of optical water properties at a new possible detector site in the Pacific. Their successor STRAW-b, currently under development at the TUM Physics Department, will complement the measurements of STRAW. We test new engineering and deployment strategies, scaleable for larger setups with up to one hundred mooring lines.

In some pre-main-sequence stars such as T Tauri  stars, the short-wavelength (high-energy) flux is stronger than what is  predicted by the rest of the SED, which peaks longwards of the visible.  The most reliable explanation for this excess emission is that these young stars are still accreting from their  protoplanetary disk. Indeed, the release of gravitational energy lets  the accreting gas reach temperatures of 10^5 K or more, while keeping  the stellar photospheric temperature low.

Very recently, such high-energy excess photons from  planets were also detected, in part with high spectral resolution. These  observations are a precious clue to understanding the timescales of  planet formation and the geometry of the accretion.

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

Recent observations have revealed protoplanets embedded in protoplanetary disks, providing precious clues towards understanding the timescale and dynamics of planet formation. Particularly, the detected Hα emission suggests temperatures of ~10 eV. Gas accreting onto forming giant planets, and forming an accretion shock, is a convincing candidate.

To shed light on this emission, we have constructed a numerical model of shock-heated gas with cooling, chemical reactions, and non-equilibrium radiative transfer in the postshock region. We also take into account the absorption of the radiation by the preshock gas. We present and apply this model to recent observational results and demonstrate how spectrally-resolved emission lines constraint the properties of forming gas giants.

ESO Mini-workshop

ESO Auditorium "Eridanus", 14 February 2020

Women in STEM and the challenges they face

10:00 - 10:30 Chiara Pedersoli (OHB System AG): “A dream comes true? My experience in the European space industry”

10:30 - 11:00 Constanza Araujo Hauck (ESO): “Challenges of being a woman in engineering” (TBC)

11:00 - 11:30 Nando Patat (ESO): “Gender bias in telescope time allocations”

11:30 - 12:00 Mariella Stockkamp (LMU): “Facilitating Women - Interrupting the Process of Stereotype Threat”

12:00 - 12:30 Open discussion

Organized by: ESO Diversity & Inclusion Committee

In celebration of the United Nations International Day of Women and Girls in Science on Tuesday 11 February

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.

Back in 2018, the interdisciplinary project "A Global Approach to the Gender Gap in Mathematical and Natural Sciences: How to Measure It, How to Reduce It?” launched a Joint Global Survey to learn about the educational and career paths of scientists and academics with a degree and/or a professional career in STEM. The survey collected more than 30,000 responses, from all over the world and from six different scientific disciplines. After a short introduction to the project, I will highlight and discuss the main results of the Joint Global Survey for the field of astronomy, and compare them to the other research fields and across geographical areas.

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.

ESO and OU are collaborating on a new visible light CMOS image sensor design based on a pinned photodiode (PPD) with multiple charge transfers and sampling to allow single photon sensitivity. In the proposed sensor architecture, the photogenerated signal is sampled non-destructively multiple times and the results are averaged. Each signal measurement is statistically independent and by averaging, the readout noise is reduced to a level where single photons can be distinguished reliably. A pixel design using this method has been simulated in TCAD and layouts have been generated for a 180 nm CMOS image sensor process. Using simulations, the noise performance of the pixel has been determined. The strengths and the limitations of the proposed design are discussed, including the trade-off between noise performance and readout rate and the impact of charge transfer inefficiency. The projected performance of our first prototype device indicates that single photon imaging is within reach and could enable ground-breaking performance in many scientific and industrial imaging applications. We will also discuss the potential uses of this detector type for astronomy and welcome robust discussion in the Q&A session about the how this sensor could be used in future astronomical instruments.

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

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

In star-forming cores and filaments, high deuteration fractions have been inferred via APEX and ALMA observations, through the comparison of deuterated and non-deuterated species like N2D+ and N2H+. As the deuteration process occurs as a result of non-equilibrium chemistry, the deuteration fraction is often considered as a potential chemical clock to determine approximate ages in prestellar cores. To investigate this possibility, we have conducted 3D magneto-hydrodynamical simulations including a network for deuteration chemistry by Walmsley et al., to explore how deuterium fractionation builds up under realistic conditions. We show that the observed fractions can be reached within about a collapse time for a vast range of possible conditions. I will also present extensions of these simulations towards filaments and including freeze-out on dust grains.

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 vast majority of all stars, including virtually all known planet hosts (and our own Sun), will end their lives as white dwarfs: small and dense stellar embers.

Planetary system can survive the late evolution of their host star and remnants of these planets can be observed as pollutants in the otherwise pristine atmospheres of some white dwarfs. Spectroscopic observation and accurate modelling of these polluted white dwarf allows to study the bulk composition of rocky exo-planets, a property simply inaccessible by radial velocity and transit observations of planets around main sequence stars. 

I will give a brief overview of the state of the art of this promising field and present some recent exciting results.

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

Exploring the low surface brightness (LSB) universe is one of the most challenging tasks in the era of the deep imaging and spectroscopic surveys. It is however a crucial ingredient to map the mass assembly of galaxies at all scales and all environments and thus constrain their formation within the Lambda-Cold Dark Matter paradigm. In this framework, clusters of galaxies are expected to grow over time by accreting smaller groups. During the infall process, the material stripped from the galaxy outskirts builds up the stellar halos and the intra-cluster light (ICL). These are extended (> 10 Re), diffuse and very faint (μ_g > 26 mag/arcsec^2) components made of stars stripped from satellite galaxies, also in the form of streams and tidal tails, with multiple stellar population and complex kinematics, which are still growing at the present epoch.

In the past, the main limitation of the above studies is the small field of view and angular resolution of the CCD images.

The advent of wide-field cameras allows to overcome these limits and thus to study the very out and faint regions of galaxies. Therefore, on the observational side, a big effort was made in the recent years to develop deep photometric surveys aimed at studying galaxy structures out to the regions of the stellar halos (e.g. Ferrarese et al. 2012; van Dokkum et al. 2014; Duc et al. 2015; Munoz et al. 2015; Merritt et al. 2016; Trujillo & Fliri 2016; Mihos et al. 2017; Iodice et al. 2019). With the current observing facilities the galaxy outskirts and intra-cluster regions can be effectively probed down to a surface brightness limit of ~ 31 mag/arcsec^2 in the g band for nearby galaxies (≤ 50 Mpc).

In this mini-series of KES lectures I would like to

- review the main progresses made on both observational and theoretical sides on this scientific topic;

- show the main steps to derive from the deep images a set of observables to be directly compared with the theoretical predictions on the mass assembly. This part will include details on observation strategies and tools adopted in deep surveys;

- compare results from the analysis of the deep images with simulations.

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.

First theorized roughly 50 years ago, I will give a brief introduction to the Sunyaev-Zeldovich (SZ) effect, which probe the warm and hot ionized gas in large scale structures at frequencies ~15-500 GHz.  I will then describe how ALMA and the ACA make extremely sensitive but fundamentally limited measurements of the SZ effect, and talk about ways we can improve this in the near future.

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

The evolution of young stellar objects (YSOs) from the Class0/I phase, when they are surrounded by an envelope, to the Class II phase, when the envelope is dissipated, is a key phase to understand in order to determine how planets form.

During this phase one of the most interesting physical phenomena is the accretion of mass from the envelope, through the circumstellar disk, and onto the star.

The accretion process has been well investigated and quantified in the last years for 1-3 Myr old, and even older YSOs. On the contrary, the strength and properties of accretion in the earlier stages (age<1 Myr) is starting to be studied only recently thanks to the new instrumentations, such as VLT/KMOS. 

Here, we present the results of the analysis of the KMOS IR spectra for a sample of YSOs in the young (~1Myr) cluster NGC1333 in the Perseus star-forming region. We compare the accretion rates with those derived in older regions to obtain information about the evolution of the accretion luminosity and the mass accretion rate with the age and evolutionary stage of the YSOs population.

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.

The early formation of supermassive black holes a billion years after the Big Bang is challenging our understanding of structure formation at Cosmic Dawn. The growth time for black holes is, indeed, relatively short, with an e-folding time scale of only 45 Myr when accreting at the Eddington limit. This implies that a black hole seed needs to maximally accrete for the entire Cosmic time to reach a mass >10^8 Msun by z~6. However, this is not the only timescale in play. In this presentation I will summarize results from our 3D pan-chromatic view of the first quasars (capitalizing on ALMA, XSHOOTER, and MUSE data) and provide some pencil and paper (or better, chalk and blackboard) estimates on the relevant timescales connecting the inter- and circum-galactic medium, the quasar host galaxy, and the accretion of the central black holes in the most massive galaxies at the dawn of the Universe.

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

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.

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