Seminars and Colloquia at ESO Garching and on the campus

May 2021

12/05/21 (Wednesday)
10:30, Webinar | ESO Garching
MPE-CAS Journal Club on Star and Planet Formation
Talk — Survival of ALMA Rings in the Absence of Pressure Maxima
Haochang Jiang (Tsinghua University)
12:00, Webinar | ESO Garching
Lunch Talk
Talk — Unveiling the populations in the inner Galaxy: Chemo-dynamical analysis
Anna Barbara Queiroz (AIP)

Abstract

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

17/05/21 (Monday)
10:45, Webinar | ESO Garching
KES: Knowledge Exchange Series
Talk — (topic to be announced)
Joe Anderson (ESO)
18/05/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Probing the effects of environment on star and brown dwarf formation
Karolina Kubiak (CENTRA, Faculdade de Ciências, Universidade de Lisboa)

Abstract

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — The Outflow Legacy Accretion Surveys (OLAS): simultaneous panchromatic observations of the low mass X-ray binary Swift J1858
Noel Castro Segura (University of Southampton)

Abstract

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

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

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

19/05/21 (Wednesday)
15:00, Webinar | ESO Garching
Informal Discussion
Talk — Reflexive Metrics – Reactivity and practices of quantification in research evaluation in Astronomy
Julia Heuritsch (HU Berlin)
20/05/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Constraining Galaxy Formation and Baryonic Effects on LSS with Observations of the Thermal and Kinetic Sunyaev-Zeldovich Effects
Nicholas Battaglia (Cornell University)
25/05/21 (Tuesday)
15:00, Webinar | ESO Garching
ESO Cosmic Duologues
Amina Helmi & Ana Bonaca (Kapteyn Astronomical Institute, University of Groningen, NL & Jeremiah Horrocks Institute, University of Central Lancashire, Preston, UK)
26/05/21 (Wednesday)
12:00, Webinar | ESO Garching
Lunch Talk
Talk — A Journey across Hertzsprung-Russel diagram with 3D hydrodynamical simulations of cool stars
Andrea Chiavassa (OCA & ESO Visitor)

Abstract

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

27/05/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Chemistry of Planet Formation
Karin Öberg (Harvard University)

June 2021

01/06/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Atmospheric Dispersion Corrector: From design phase to on-sky commissioning
Bachar Wehbe (Institute of Astrophysics and Space Sciences (IA))

Abstract

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Stellar population gradients of SAMI central galaxies
Giulia Santucci (University of New South Wales)

Abstract

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

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

02/06/21 (Wednesday)
10:45, Webinar | ESO Garching
Informal Discussion
Talk — (topic to be announced)
Michele Ginolfi (ESO)
07/06/21 (Monday)
10:45, Webinar | ESO Garching
KES: Knowledge Exchange Series
Talk — (topic to be announced)
Joel Vernet (ESO)
08/06/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Exploring the metal-poor inner Milky Way with the Pristine survey
Anke Arentsen (Observatoire astronomique de Strasbourg)

Abstract

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

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

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Calibrating the Cepheid distance scale with Gaia
Louise Breuval (Paris Observatory (LESIA))

Abstract

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

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

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

09/06/21 (Wednesday)
12:00, Webinar | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Dylan Bollen (Institute of Astronomy, KU Leuven)
10/06/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Jenny Greene (Princeton University)
15/06/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Cosmic telescopes: witnessing the emission mechanism of radio quiet quasars
Philippa Hartley (Square Kilometre Array Organisation, University of Manchester)
15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — On the flaring of Thick Discs of Galaxies: Insights from Simulations
Joaquin Garcia de la Cruz (Liverpool John Moores University)

Abstract

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

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

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — On the flaring of Thick Discs of Galaxies: Insights from Simulations
Joaquin Garcia de la Cruz (Liverpool John Moores University)
16/06/21 (Wednesday)
10:45, Webinar | ESO Garching
Informal Discussion
Talk — (topic to be announced)
Tiago Costa (MPA)
17/06/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Sera Markoff (University of Amsterdam)
21/06/21 (Monday)
10:45, Webinar | ESO Garching
KES: Knowledge Exchange Series
Talk — (topic to be announced)
Pierre-Yves Madec (ESO)
22/06/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Cosmic Dissonance: new physics or systematics behind a short sound horizon?
Nikki Arendse (DARK Niels Bohr Institute, University of Copenhagen)

Abstract

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

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

 

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Photoionized Herbig-Haro objects in the Orion Nebula through deep high-spectral resolution spectroscopy
Jose Eduardo Mendez-Delgado (Instituto de Astrofísica de Canarias)

Abstract

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

23/06/21 (Wednesday)
14:00, Webinar | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Paula Jofré (Universidad Diego Portales)
24/06/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Gravitational waves
Rainer Weiss (MIT)

July 2021

01/07/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Andrea Isella (Rice University)
06/07/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Unveiling the chemical composition of the Small Magellanic Clou
Alice Minelli (DIFA - UNIBO (Dipartimento di Fisica e Astronomia - Universitá di Bologna))

Abstract

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

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Dust-depleted Inner Disks in a Large Sample of Transition Disks through Long-baseline ALMA Observations
Logan Francis (University of Victoria)

Abstract

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

07/07/21 (Wednesday)
12:00, Webinar | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Nicolas Crouzet (ESA)
08/07/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Frederic Daigne (Institut d'Astrophysique de Paris)
13/07/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — Blue straggler stars in open clusters
Maria Jose Rain (University of Padova)

Abstract

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Unveiling the multiphase ISM of z>6 quasar host galaxies with ALMA
Antonio Pensabene (INAF-Astrophysics and Space Science Observatory of Bologna)

Abstract

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

15/07/21 (Thursday)
15:15, Webinar | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Carlo Rovelli (Université de Aix-Marseille)
20/07/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — From clouds to crust - Cloud diversity and surface conditions in atmospheres of rocky exoplanets
Oliver Herbort (St Andrews Centre for Exoplanet Science)

Abstract

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — The Athena/X-IFU instrument, from detector development to scientific feasibility studies
Sophie Beaumont (IRAP & NASA GSFC)
27/07/21 (Tuesday)
15:00, Webinar | ESO Garching
Hypatia Colloquium
Talk — High-z Lyman Break Galaxies with JWST: parallel observations of dwarf satellites
Viola Gelli (University of Florence)

Abstract

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

15:30, Webinar | ESO Garching
Hypatia Colloquium
Talk — Modelling galaxy emission-line kinematics using self-supervised learning
James Dawson (Cardiff University)

Abstract

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