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• Monday February 23: Olivia Venot
• Monday February 9: Francesca Lepori
• Monday February 2: Anna Gallazzi
• Monday January 26: Payel Das
• Monday January 12: Bart Vandenbussche
• Monday December 15: Nathan Mayne
• Monday December 1: Natalia Lahén - "Mergers all the way down: simulating the origin of globular clusters in a galactic context"

  Abstract: Observations with the JWST have now revealed that massive star clusters at high redshifts formed with high mean stellar surface densities. These clusters are thought to represent the progenitors of globular clusters (GCs) that are nowadays found in practically all galaxies but whose origins remain poorly understood. In the dense, low-metallicity conditions of hierarchical proto-GC formation, massive stars and black holes have been theorized to grow in mass due to collisions while the star-forming gas is being self-enriched by stellar winds of massive stars. In this talk I will explore the formation of star clusters in such extreme environments by presenting the results of star-by-star hydrodynamical simulations of low-metallicity dwarf galaxy starbursts. The simulations account for a multiphase interstellar medium, stellar radiation, winds and supernovae, and accurate small-scale gravitational dynamics near massive stars. The latest simulation includes prescriptions for the collisional growth of very massive stars and tidal disruption events by stellar black holes. I will discuss our results for the galactic population of star clusters, concentrating on the internal structure and chemical contents of massive clusters where the hierarchical formation history leaves a kinematic imprint in their stellar populations.

  Host: Katja Fahrion
• Monday November 24: Qiao Xue - "Hot rocky planets through NIRSpec's eyes: what we learned from phase curves"

  Abstract: Rocky planets orbiting M dwarfs lie at the frontier of characterizing exoplanet atmospheres: they are the most common planets in our universe, and their planet-to-star radii ratio makes them favorable for observation follow-ups. However, intense stellar irradiation can strip primordial volatiles, and the threshold at which atmospheres are lost in these worlds remains uncertain. Detecting atmospheres on rocky planets around M dwarfs through secondary-eclipse measurements with JWST’s Mid-Infrared Instrument (MIRI) is a central goal of multiple GO programs and the ongoing Rocky Worlds DDT program. In this talk, I want to present results for two rocky planets that probe a previously unexplored range in irradiation (Tirr) space—TOI‑2445 b and TOI‑1685 b. We obtained full-orbit JWST/NIRSpec phase curves with PRISM for TOI‑2445 b and G395H for TOI‑1685 b.From the corrected phase curves, we retrieve dayside and nightside brightness temperatures for both planets, constraining their albedos and heat redistribution efficiencies, which are key diagnostics for the presence or absence of an atmosphere. Finally, we place these results in a population context by combining our NIRSpec phase curves with existing MIRI/LRS, imaging and DDT data on rocky planets. Together, the data will map out a more complete brightness temperature - Tirr space, guiding future atmospheric searches on JWST and beyond.
• Monday November 17: Adam Ginsburg - "What sets stellar masses in the Galaxy's richest environments?"

  Abstract: The most important factor deciding the fate of a star and its surroundings is its initial mass.  The relative number of high- and low-mass stars decides how much light and mass escape from a population of stars.  This distribution, the stellar initial mass function, is often assumed to be universally invariant, though we have plenty of reason to believe it varies with environment.  I will present results from ALMA observations, including large programs ALMA-IMF and ACES, that measure the mass distribution of pre- and proto-stellar objects at early phases.  Denser regions of our Galaxy, like its center, form more stars in clusters than do the outskirts where the Sun resides.  Core mass function measurements suggest that more intensely star-forming regions preferentially form high-mass stars.  However, the simplest models of core-to-star evolution fail, and I'll show how some have been ruled out using detailed observations of the massive cluster-forming regions W51 and Sgr B2.  I'll present a new theoretical framework based on linking radiative transfer models to protostellar accretion history models that we're using to interpret this transition.  Finally, I'll show how JWST is changing our view of young and forming massive clusters and their icy environments with a gallery of early results from several imaging programs.
• Monday November 10: Sebastian Kamann - "Understanding the evolution of massive star clusters through their binary stars"

  Abstract: Massive star clusters, like the globular clusters hosted by the Milky Way, are important tracers of galaxy evolution. Not only do their ages and chemical compositions preserve a history of star formation, but they also hold the key to advance our understanding of the growth of black holes. Both the mergers of stellar back holes and the seeding of supermassive black holes have recently been linked to massive star clusters. To gain a better understanding of cluster evolution, studies of their binary star populations are crucial: Binary stars strongly impact the energy balances of their host clusters, they are responsible for stellar exotica like blue stragglers, and they provide us with a rare opportunity to detect quiescent black holes. In my talk, I will give an overview of our binary population studies in both young massive clusters and ancient globular clusters in the Local Group, using integral-field spectroscopy. With instruments such as MUSE and FLAMES, we monitor large samples of cluster stars with the aim of constraining the orbits and measuring the companion masses of detected binary stars. I will also discuss the challenges involved in finding stars bound to black holes and the implications for our understanding of gravitational wave detections.
• Monday November 3: Luca Tortorelli - "Forward-modelling galaxy surveys for next-generation cosmological and galaxy evolution measurements"

  Abstract: The next-generation of wide-field galaxy surveys, known as Stage IV experiments, aims to investigate the "dark sector" by mapping a significant fraction of the observable Universe at unprecedented depth. In doing so, they will also contribute to transform our understanding of galaxy formation and evolution. Their vast statistical power is however limited by systematic effects that dominate over the statistical uncertainties of the measurements, with the precise estimate of galaxy redshift distributions N(z) being one of the most critical systematic. The forward-modelling of photometric and spectroscopic galaxy surveys provides a powerful framework to address two key challenges: (i) obtaining quantitative galaxy evolution insights from characterising the galaxy population observed in Stage IV galaxy surveys and (ii) use this knowledge to obtain precise N(z) estimates that allow for conducting improved cosmological measurements. In this talk, I will discuss the past (Tortorelli+18,20,21) and on-going efforts (Tortorelli+24, Tortorelli+25) in forward-modelling galaxy surveys, from the modelling of the galaxy population (GalSBI-SPS) to the simulation of images (UFig) and spectra (USpec), as well as the data required to calibrate this model. I'll show that our forward-modelling framework already provides precise redshift distribution estimates for a Stage-III setup and that the future inclusion of constraining spectroscopic data in the modelling will lead to redshift distribution estimates that will enable cosmological and galaxy population studies with the precision required by Stage IV experiments.
• Monday October 27: Sarah Bosman - POSTPONED

  Abstract: The ionisation of hydrogen in the intergalactic medium, thought to have occurred mainly around redshift 7 or 8, was a unique cosmological epoch when the first stars had a drastic impact on the Universe as a whole. Reionisation offers an opportunity to check the agreement between our understanding of large-scale structure formation and galaxy formation. In recent years, the end stages of reionisation have been studied in excellent detail with the Lyman-alpha forest, even providing a precise ending time for the process. However, this ending time is in tension with observations of the first galaxies by the James Webb Space Telescope, and some reionisation theorists are re-evaluating classical assumptions on the required "budget" of UV photons to complete reionisation. In this talk, I will review these recent breakthroughs and challenges.
• Monday October 20: Mar Carretero - "Massive runaway stars in the Milky Way: new insights from Gaia and beyond"

  Abstract: A relevant fraction of massive stars are runaway stars, moving with large peculiar velocities relative to their environment. These fast-moving stars can interact with the interstellar medium, producing structures such as stellar bow shocks. Their runaway origins can be explained by two main mechanisms: dynamical ejections from young stellar clusters and supernova explosions in binary systems. A combination of both mechanisms is also possible. Therefore, massive runaway stars are important to better understand clusters and the late stages of massive binary evolution. In this talk, I will introduce a new method to identify massive runaway stars in the Milky Way using Gaia data, together with their multi-wavelength characterization. I will also present an extensive observational study of their rotation and binarity, providing new insights into runaway ejection mechanisms and their possible connection with high-energy binary systems. 
• Monday October 13: Anne Hutter - "Illuminating the first billion years with the cosmic 21cm signal"

  Abstract: The cosmic 21cm signal from neutral hydrogen offers a unique window into the large-scale structure of the Universe during the Dark Ages and the ionisation morphology of the Epoch of Reionisation. Multiple radio interferometers are currently searching for this faint signal, which remains hidden beneath foregrounds several orders of magnitude brighter. Although continuous progress has been made in foreground mitigation and signal extraction, a definitive detection has not yet been achieved. The sensitivity of current and upcoming instruments, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), should make a first detection possible in the near future. But what can we learn once we do detect the 21 cm signal? In this talk, I will briefly introduce the physical processes shaping the 21cm signal during the first billion years, review the current observational status, and discuss how statistical analyses of the 21cm signal - alone or in combination with galaxy surveys - can shed light on how the intergalactic medium was reionised and what this reveals about the properties of the first galaxies.
• Monday June 23: Sergey Khoperskov - "Assembly theory of the Milky Way galaxy"

  Abstract: Understanding galaxy formation and evolution stands as a fundamental objective in modern scientific research. However, a comprehensive observational and theoretical framework that can account for the vast range of properties observed in galaxies throughout the Universe remains elusive. In this context, the Milky Way is special, as it provides the unique opportunity to investigate complex galaxy assembly processes by studying its resolved stellar populations. Nowadays, knowledge about all Galactic components, from the halo to the disc(s) and bulge, is undergoing a profound revolution thanks to the ESA’s astrometric mission Gaia. Gaia has provided detailed measurements of stellar positions, motions, and parallax for over a billion stars, offering a comprehensive map of our galaxy. Complementing this, spectroscopic data from surveys such as APOGEE, GALAH, GES, and others provide us with stellar parameters, chemical abundances, ages and velocities. In this talk, I will present what we have learned about the Milky Way using the synergy between large observational data sets, various modeling techniques and state-of-the-art galaxy formation simulations. This integrated approach has led to an in-depth understanding of the disc mass assembly history, the impact of the bar and spiral arms, the formation and present-day structure of the bulge, and the build-up of the Milky Way's stellar halo. I will also discuss how our detailed knowledge about the Milky Way can be used to fill the gaps in our picture of galactic evolution in general.
• Monday June 2nd - Special Event by Research Services and Career Development: "Mentoring for postdocs - strategies for mentors and mentees"

  Special Time: 14:00-17:30

  Location: Littrow Hörsaal

  Event website: forschung.univie.ac.at/mentors/

   

  Description:

  This event will bring together experienced mentors, institutional stakeholders, and academic leaders to highlight the importance of mentoring in the postdoctoral phase.At our university, mentoring is already practised in many forms – often without being explicitly labelled as such. We aim to identify how these valuable practices can be reinforced, better supported, and made visible. The event also seeks to ensure that mentoring effectively supports a range of career paths, both within and beyond academia.

  Program:

  14:00-14:30 | Arrival

  14:30-14:45 | Welcome address - Vice Rector

  14:45-15:45 | KeynoteL Nicole Wedell von Leupoldt (KU Leuven Career Center)

  15:45-16:00 | Coffee Break

  16:00-17:30 | Panel discussion: (Mentoring Postdocs for Careers (inside and beyond academia): What is needed? With Vice-Rector Manuela Baccarini, Nicole Wedell von Leupoldt (KU Leuven), Susanne Hochreiter (Equal Opportunities Working Party), Dagmar Woebken (CeMESS)

  17:30 | Closing & Summer reception

   

  Additional:  
  * Open pinboards: "University of Vienna Mentors of Postdocs need..." 

  * Morning session: Earlier that day, we will also host a dedicated event for postdocs - "Mentoring for Postdocs – The Mentee Edition."  If you are also interested in attending this session, please don't hesitate to get in touch at the above link.
• Monday May 26th: Tereza Jerabkova - "The Stellar Initial Mass Function: From Small Structures in the Milky Way to Giants at High Redshift"

  Abstract: The stellar initial mass function (IMF) lies at the heart of many astrophysical problems—from interpreting galaxy light to modeling feedback and chemical enrichment. Yet, despite its centrality, the IMF remains an elusive quantity: it does not truly exist in nature, varies with environment, and continues to challenge our understanding of star formation. In this talk, I will take a journey through the IMF’s historical origins, current state, and why it continues to give theorists and observers a headache. I will highlight recent observational and theoretical results across scales, from Milky Way star-forming regions to massive high-redshift galaxies, and question whether we even need IMF as a concept. As a lighter interlude, I will also introduce the Dog Initial Mass Function. Finally, I will briefly present the new Stellar Populations in Galaxies group at Masaryk University in Brno and its research directions.
• Monday May 5th: Conor Nixon - POSTPONED
• Monday April 28th: Zoltan Haiman - "Gravitational wave and electromagnetic signatures of binary black holes with circumbinary gas"

  Abstract: Binary black holes (BHBs) embedded in dense gas hold the
  promise of so-called "multi-messenger astrophysics": when they are
  detected both through gravitational waves (GWs) and electromagnetic
  (EM) observations, they will enable novel science. This is true both
  for massive BHBs, whose GWs will be detectable by the future LISA
  satellite and by on-going pulsar timing arrays (PTAs), as well as for
  stellar-mass BHBs detected through ground-based GW detectors. In both
  cases, identifying the coalescing binaries through their EM signatures
  will help clarify their astrophysical origin and yield novel probes of
  cosmology, fundamental physics, and accretion physics. In this talk,
  I will describe how circumbinary gas may produce characteristic EM
  signatures for both massive and stellar-mass BHBs, based on analytic
  models as well as hydrodynamical simulations. I will also argue that
  in both cases, some coalescing binaries may have already been detected
  in optical surveys, providing clues about their origin.

  Host: Oliver Hahn
• Monday April 14th: Ekaterina Ilin - "Channeling sparks through interplanetary space: magnetic star-planet interactions"

  Abstract: Planets in short orbits — less than 10 days — are absent from our own solar system, but they are among the easiest to detect around other stars. At such close distances, a new phenomenon emerges: the planet can have a measurable effect on its star through tidal or magnetic interactions. Magnetic interaction, in particular, is crucial for understanding not only the evolution of these close-in planets but also of those farther out in the habitable zone. In this colloquium, we'll review the basic mechanisms behind these interactions, contemplate intriguing systems that may be interacting, learn why detecting magnetic star-planet interaction is challenging, and explore how this challenge can be overcome. Come if you want to immerse yourself in the dazzling tango between planets and their host stars, rack your brain against a tough observational problem, and see a planet self-roast in real time.

  Host: Kristina Kislyakova
• Monday April 7th: Matthieu Schaller - "The FLAMINGO hydrodynamical simulation suite: A precision cosmology survey virtual twin"

  Abstract: The accuracy of the interpretation of the current generation of late-time cosmology probes is greatly limited by the theorists' ability to predict the response of baryons. This will only get more difficult in the coming years with the upcoming surveys (DESI, Euclid, LSST, 4-most) mapping our sky with unprecedented precision. In this talk, I will discuss some of the efforts towards this challenge on the simulation side. I will, in particular, focus on the required developments in the SWIFT code and the new generation of simulations, the FLAMINGO suite, designed to be virtual twins of the Stage IV cosmology surveys. This suite includes the largest simulation ever run to z=0 and exploits a state-of-the-art baryon physics model calibrated to the relevant data. Variations in the physics, trained via machine learning techniques, allow us to encompass the uncertainty in the modeling. Outputs in observer space, such as X-ray, stellar light and SZ lightcones are produced and are used to validate the simulations. I will conclude by presenting a selection of key results obtained in the last year or so by exploiting the simulation data. This talk is a invitation to make use of this data for your research.

  Host: Sylvia Plöckinger
• Monday March 31st: Kai Polsterer - POSTPONED

  Abstract:

  Host: João Alves
• Monday March 17th: Sebastián Marino - "Studying ExoKuiper belts through ALMA observations"

  Abstract:Planetary systems are composed of not only planets but also minor bodies similar to asteroids and comets, which we typically find in belts analogous to the asteroid and Kuiper belt in the solar system. Although we cannot detect these bodies individually, mutual collisions between these km-sized planetesimals produce high dust levels that are readily detectable in exoKuiper belts around 30% of nearby stars. These planetesimals form as a byproduct of planet formation and their distribution is likely shaped by the presence of planets in a similar way as the Asteroid and the Kuiper belts were shaped by Jupiter and Neptune. Therefore, these belts provide unique constraints on the formation, architecture, and dynamics of planetary systems. In this talk, I will give an overview of the study of exoKuiper belts and show our ALMA large program ARKS is constraining the detailed structure of these belts to learn about how these form in protoplanetary discs and evolve over Gyr timescales.

  Host: Nicole Pawellek
• Monday March 3rd: Ignacio Martin Navarro - "Bending the rules of stellar population modeling"

  Abstract: Stellar population models are relatively simple yet arguably the most powerful tools to study the light emitted by distant galaxies. In this talk I will present our recent efforts to put to the tests their current capabilities. In particular, I will describe their use as cosmological probes and how the detailed analysis of absorption spectra can set direct constraints on the universality (or not) of the stellar initial mass function. Finally, I will also discuss alternative approaches going beyond what is possible with state-of-the-art evolutionary stellar population synthesis models.
  

  Host: Alina Boecker
• Monday Feb. 24: Francesca Fragkoudi - "The formation, evolution, and dark matter content of barred galaxies in LCDM"

  Abstract: The advent of high resolution hydrodynamical cosmological simulations allows us to now study the internal dynamics of barred spiral galaxies -- such as our own Milky Way -- within the full ΛCDM cosmological context. I will present what we have learnt about the formation and evolution of barred galaxies by comparing cosmological simulations to observations of both the Milky Way and nearby spiral galaxies. In particular, I will address the "When?" and the "How?" of bar formation in ΛCDM, and discuss what this implies about our own Galaxy's formation history, as well as why some galaxies form bars and others don't. I will discuss how barred galaxies evolve throughout cosmic history, as well as the connection between bars and their host dark matter halos, which can help shed light on both the amount and the nature of dark matter.
• Monday Feb. 17: Nadeen Sabha ** POSTPONED **
• Monday Feb. 10: Julio Navarro - "Dark Matter Clues from the Faintest Galaxies"

  Abstract: Lambda Cold Dark Matter (LCDM) is the most successful theory for the formation of structure in the Universe. Although its predictions have been verified on large scales, they are still contested on the scale of dwarf galaxies, whose dynamical properties are often cited as evidence for the need to revise some of LCDM's basic tenets. In this context, I will discuss the recent discovery of the faintest galaxies known to date, and how their properties may be used to place constraints on the clustering of dark matter on the smallest galactic and sub-galactic scales, as well as on the viability of some of the proposed alternatives to LCDM.
• Monday Jan. 27: Lisa Bugnet - "The Magnetoasteroseismology revolution: how does magnetism impact stellar evolution?"

  Abstract: Understanding dynamical processes taking place below the surface of stars is key for a better estimate of stellar ages. The recent measurement of low-mass stars' slow core rotation during the evolved stages of their evolution shows the need for strong angular momentum transport processes from the core to the envelope. Internal magnetic fields, mostly ignored in stellar evolution models, are one of the most promising candidates to explain this observed strong angular momentum transport. I will review the magnetoasteroseismology revolution that has taken place in the past few years, leading to the promising detection and characterization of magnetic fields inside the core of evolved low-mass stars.
• Monday Jan. 20th: Laila Linke - **POSTPONED **
• Monday Jan. 13: Jozsef Varga - "The inner region of planet forming disks from VLTI observations"

  Abstract: In the last decade, groundbreaking discoveries with high angular resolution facilities like ALMA and SPHERE revealed the rich sub-structure of planet-forming disks on tens of au spatial scales. However, the inner region of disks (r < 10 au), the birthplace of terrestrial planets, has remained relatively unexplored. Currently, infrared interferometry with facilities like ESO's Very Large Telescope Interferometer (VLTI) is the only technique to get spatially resolved information on that area. The VLTI/MATISSE Guaranteed Time Observations team, which I am part of, is conducting a multi-year large survey of about a hundred planet-forming disks, with the aim to create a systematic overview of inner disk sub-structures and dust composition. The majority of our objects are Class II Herbig AeBe and T Tauri disks. In my talk, I will present science highlights from the first five years of our survey, showing spectacular case studies. One such case is the disk of HD 144432 where VLTI's sub-au angular resolution allowed us to detect a three-ringed structure in the inner 5 au. The relatively short dynamical timescales in the inner disk enable us to track the motion of asymmetric dust features in 'real-time', using monitoring observations over a period of weeks to months. I will show how such observations reveal the orbital motion of clumps in the HD 163296 and in the DX Cha systems. Finally, I present the latest results on inner disk dust mineralogy from N band (8-13 micron) MATISSE observations.
• Monday Dec. 16: Azadeh Moradinezhad - " Stress-testing ΛCDM and searching for new Physics with spectroscopic galaxy surveys: from PT to AI"

  Abstract: The cosmic large-scale structure (LSS) is a treasure trove for exploring the origins, evolution, and fundamental constituents of the universe. Upcoming stage-IV galaxy surveys will deliver an unprecedented volume of high-precision data, enabling constraints on deviations from the ΛCDM model at the sub-percent level and opening new avenues for detecting signatures of new physics. To fully harness these datasets, however, we must advance beyond current analysis techniques to optimally extract the non-Gaussian information embedded in the LSS. Moreover, as statistical uncertainties shrink, addressing observational systematics becomes crucial to ensure unbiased and robust cosmological constraints. In this talk, I will present recent efforts to quantify the information content of alternative summary statistics beyond the galaxy power spectrum. I will highlight the potential of machine learning, particularly simulation-based inference, in enhancing cosmological constraints beyond what is achievable through standard theory-based approaches. Additionally, I will discuss a specific application of machine learning to observational noise removal, showcasing how relatively simple techniques can significantly improve data quality.
• Monday Dec. 9: Jacqueline Hodge - "Lifting the veil on galaxy formation at high-redshift"

  Abstract: A substantial fraction of the Universe's star formation is heavily enshrouded by dust, and this basic fact has long been a hindrance to the development of a complete picture of galaxy evolution. Now, thanks to the advent of powerful telescopes including the Karl G. Jansky Very Large Array (VLA), the Atacama Large Millimeter Array (ALMA), and most recently, the James Webb Space Telescope (JWST), our view of dusty star formation at high-redshift is undergoing a radical transformation. I will present ALMA+JWST imaging of the dustiest galaxies in the Universe, finally revealing their nature for the first time more than 20 years after their discovery. I will discuss our latest efforts to directly detect the cold gas reservoirs fueling their intense star formation. Finally, I will share our attempts to push such multi-tracer studies to within the Universe's first billion years, including our discovery of the earliest rotating disk galaxy known to-date, and I will discuss how this discovery may challenge our traditional view of early galaxy formation.
• Monday Nov. 25: Martyna Chruslinska - "Stellar black hole mergers: astrophysics with a hodgepodge"

  Abstract: The rate of gravitational wave detections will soar from hundreds to millions per year as detectors improve, revealing the population properties of BH mergers in great detail. Such properties encode valuable information about how stars form and evolve in galaxies very different from our own. They can provide complementary constraints on the cosmic chemical history and on star formation in environments that evade electromagnetic observations.However, the use of GWs in astrophysics presents challenges that must be overcome to realise their full potential.In particular, the astrophysical "interpretation challenge" that I will discuss in my talk. The observable BH merger population contains a mixture of systems formed throughout the Universe: they evolved from stars born with different chemical compositions and in very different environments (e.g. sparse stellar environments or dense clusters). Such conditions strongly influence the formation of BH mergers and can degenerate into their observable population properties. One aspect that is key to breaking such degeneracies, and on which I will focus, is constraining the iron-dependent cosmic star formation history.
• Monday Nov. 18: Laura Kreidberg - "A JWST View of Exoplanet Atmospheres: Everything We Dreamed Of, and More"

  Abstract: 

  The recent launch of the James Webb Space Telescope (JWST) has revolutionized the field of exoplanet atmosphere characterization, thanks to its unprecedented sensitivity and broad wavelength coverage. In this talk, I will give a tour of the latest JWST results for transiting exoplanets, from gas giants down to rocky worlds. For the largest planets, I'll focus on the complex physical processes recently revealed in their atmospheres, including photochemistry, 3D effects, and cloud formation.  Pushing down to smaller worlds, I'll share the first measurements of chemical composition for the elusive sub-Neptune population; and finally give an update on which (if any) rocky planets have atmospheres at all.
• Monday Nov. 11: Sherry Suyu - "Strongly Lensed Supernovae: Past, Present and Future"

  Abstract: 

  Strongly lensed supernovae (SNe) are emerging as a new probe of cosmology and SN.
  The time delays between the multiple images of a lensed SN can be used to determine
  the Hubble constant (H0) that sets the expansion rate of the Universe. 
  An independent determination of H0 is important to ascertain the possible need of 
  new physics beyond the standard cosmological model, given the tension in current 
  H0 measurements. While strongly lensed SNe are rare, the first lensed SN systems 
  are being discovered in the past few years. I will give an overview of these first
   discoveries and their cosmological results. Future surveys, particularly the 
  Rubin Observatory Legacy Survey of Space and Time, are expected to yield hundreds
  of such exciting events. I will highlight a new program aimed to find and study 
  lensed SNe for cosmology and stellar physics.
• Monday Nov. 4: Torsten Enßlin - "- "A 3D atlas of the Milky Way using information field theory"

  Abstract: Our view of the cosmos has been 2D for centuries. Thanks to the Gaia satellite, we now know the 3D positions of a billion stars.  These can be used as reference points to map the components of the interstellar medium between them in 3D. However, measurements of the components are sparse, incomplete, often only 2D, and noisy. To obtain 3D maps of the component fields, the missing information must be compensated for by our knowledge and physical understanding. Information Field Theory (IFT) is a mathematical formalism that allows such a fusion of measurements and knowledge into field estimates. This talk will introduce IFT, show how it applies to galactic cartography, and explain why a 3D Milky Way Atlas seems within reach.
• Monday Oct. 28: Morgan Fouesneau - "Gaia: A 10-year revolution in stellar astrophysics""

  Abstract: Gaia's data promises to construct the most detailed view of the chemo-dynamics of field star populations in our Galaxy. In this presentation, I aim to persuade you that Gaia has already revolutionized every aspect of astrophysics, from Galactic archeology and stellar evolution to planets and the interstellar medium. As the Gaia spacecraft approaches its imminent retirement, I will review some of its most important contributions to our understanding of the Galaxy. I will also offer a glimpse into the future, exploring the potential insights that Gaia will continue to provide even after its flight ends.
• Monday Oct. 14: Martin Groenewegen - "J-AGB stars as a new standard candle"

  Abstract: To investigate possible ways to resolve the Hubble tension other stellar distance indicatorsthan cepheids, TRGB and SNIa and have seen a renewed interest in the past years.The Mira PL-relation is one of them, but in this talk I will discuss the so-called J-AGB starsthat were introduced by Madore and Freedman as recently as 2020.The name refers to the fact that the sample of interest are (carbon) stars located inregion J of the classical 2MASS colour-magnitude diagram of the LMC by Weinberg and Nikolaev (2001)and that the J-band magnitude is the magnitude of interest to provide the standard candle.Some have advocated that the mean magnitude in a certain range in (J-K) colour is independentof metallicity and provides the standard candle. However, the situation is more complicated as pointed out already in the literature.Here I will give an introduction to the subject, provide some new results on the SMC, LMCand the Milky Way, and discuss very recent developments in the literature using JWST data.
• Monday Oct 7: Mei Ting Mak - "Simulating Haze Exoplanets: from Earth-like to Hot-Jupiter"

  Abstract: Hazes, solid-state photochemical product, are expected to be present from the early Earth to exoplanets. However, our limited knowledge of haze and the lack of studies are presenting a significant barrier in our understanding of its impact on the atmospheric dynamics, as well as interpreting observations. In this talk, I will present results from 3D simulations of photochemical haze in the atmosphere of the Early Earth, TRAPPIST-1e and WASP-39b using the 3D general circulation model - the Met Office Unified Model. For rocky planets, we found global warming and cooling when the haze layer is thin and thick, respectively. The results have implications on habitability in other planets. For hot-Jupiter, hazes accumulate in the planet's nightside vortices, resulting in observational asymmetries over the morning and evening terminators. Our results also suggest that the potential haze present in the atmosphere of WASP-39b is likely to have a weaker absorption strength than soot-like haze, contradicting the haze type commonly used by the community. These studies show the importance of understanding the impact of haze to better investigate the atmospheric dynamics and observational data of any planet.
• July 25th: Viktor Tóth - "The earliest phases of star formation - linking the smallest to the large scale"

  Abstract: Some aspects of our latest view on the interstellar medium (ISM) and star formation will be discussed with special focus on the structure and physical processes of the very cold ISM. Recent results of international collaborations co-founded by the speaker will be highlighted. The expected future impact of the New Generation VLA on the field will be also briefly addressed.
• July 8th - Morgan Fouesneau - Postponed

  Postponed
• July 1st: Silvia Bonoli - "The J-PAS survey: the sky in 56 colors and the early growth of massive black holes"

  Abstract: The Javalambre Physics of the Accelerating universe Astrophysical Survey (J-PAS) has just started scanning the northern sky with 56 filters (54 narrow bands + 2 wider bands covering the entire optical range), effectively offering a low-resolution spectrum for every object detected. Before the J-PAS wide-field camera started operations,  a proof-of-concept data-set, miniJPAS, was acquired using an interim instrument. In the first half of this talk I will present the main results of miniJPAS and will give prospects for the upcoming, order of magnitudes larger, J-PAS dataset, showing the power of wide narrow-band surveys. In the second half of the talk I will give an overview on the predictions from the L-Galaxies galaxy formation model on a variety of properties linked to the birth and evolution of massive black holes. I will particularly focus on what we can learn on massive black hole growth using the recent observational constraints from the Pulsar Timing Array and JWST.
• Monday June 17: Sascha Quanz - "The LIFE mission - searching for life outside the Solar System"

  Abstract: Indications for life on extrasolar planets can be inferred via the detection of atmospheric absorption lines of so-called biosignatures, i.e., atmospheric constituents that are only present because of biological activity. Primary candidates for searches for biosignatures are terrestrial exoplanets within the immediate vicinity of the Sun, but such objects are beyond reach for current observational techniques or instruments on ground or in space. The LIFE mission (LIFE = Large Interferometer For Exoplanets) is an ambitious space mission driven by the goal to search for life on a sizable sample of nearby exoplanets. LIFE features a space-based nulling interferometer operating at mid-infrared wavelength effectively probing the intrinsic thermal emission of exoplanets. In this talk, I will describe the unique discovery space of the LIFE mission, present the current status of the concept and technology development, and emphasize the scientific advantages of investigating of observing in the mid-infrared regime if the search for extraterrestrial life is a primary goal. 
• Monday June 17: Stefanie Walch-Gassner - "The energetics of molecular clouds: reassessing the role of gravity"

  Abstract: The intricate dynamics of molecular clouds, pivotal to the formation of stars, have been a subject of our ongoing investigation. In the SILCC-Zoom simulation suite, we investigate the formation and evolution of molecular clouds within their galactic, multi-phase ISM environment. The adaptive mesh refinement (AMR) magneto-hydrodynamics simulations include a chemical network and radiative transfer. The clouds are divided into coherent and hierarchical substructures using dendrograms. A detailed virial analysis of the identified substructures unravels their energetics. We can show that substructures that mostly consist of atomic, rather than molecular gas, are always unbound. Only denser, molecular structures become "bound", but often they seem to be stabilized by ram pressure or thermal pressure rather than truly bound by self-gravity. Only a few structures are clearly gravitationally bound. Our results put the role of gravity to the test and have important implications for the low star formation rate and efficiency in molecular clouds.
• Monday June 10: Hannah Diamond-Lowe - " Hot rocks and their host M dwarfs"

  Abstract: Exoplanets outnumber stars in the Milky Way, and small worlds with radii less than 4x Earth's radius are the most common. Despite being all around us, terrestrial exoplanets are the most difficult planetary type to study because they produce small signals in techniques we use to study exoplanets and their atmospheres, such as transit spectroscopy. To maximize detection and characterization signals we take advantage of "the M dwarf opportunity," whereby the relative radii and masses between small planets and small stars boosts the transit and radial velocity signals we are looking for. Today, JWST's infrared capabilities, pointing stability, and 25 square-meter collecting area are giving us unprecedented access to rocky worlds orbiting our closest M dwarf neighbors. However M dwarf host stars are more variable than expected, and can imprint stellar molecular features on planetary transit spectra. In this talk I will present the state of the field of terrestrial exoplanet science in the JWST era, including the latest results, toughest challenges, and brightest prospects for discovery.
• Monday June 3rd: Ravit Helled - "What makes a planet 'giant'?"

  Abstract: The formation history of giant planets inside and outside the solar system remains unknown. I will present a new path for giant planet formation where runaway gas accretion is initiated only at a mass of ~100 M_Earth. This suggests that the transition to a gas giant planet, a planet that its composition is dominated in hydrogen and helium, occurs at ~Saturn’s mass. Delaying runaway accretion to later times (a few Myr) and higher masses is likely to be a result of an intermediate stage of efficient heavy-element accretion that provides sufficient energy to hinder rapid gas accretion. This implies that Saturn has never reached runaway gas accretion, and that it is a "failed giant planet". The transition to a gas giant planet above Saturn's mass naturally explains the differences between the bulk metallicities and internal structures of Jupiter and Saturn, and the characteristics of Uranus and Neptune. In terms of giant exoplanets, delaying runaway gas accretion to planets beyond Saturn's mass explains the transitions in the mass-radius (M-R) relations of observed exoplanets and the high metallicity of intermediate-mass exoplanets. 
• Monday May 27: Jia Liu - "Cosmology with Massive Neutrinos"

  Abstract:  Ghostly neutrino particles continue to bring surprises to fundamental physics, from their existence to the phenomenon of neutrino oscillation, which implies their nonzero masses. Their exact masses, among the most curious unknowns beyond the Standard Model of particle physics, can soon be probed by the joint analysis of ongoing and upcoming cosmological surveys including Rubin LSST, Euclid, Roman, DESI, PFS, Simons Observatory, CMB-S4, and LiteBRID. In this talk, I will discuss ongoing works studying the effects of massive neutrinos and will draw a roadmap towards discovering the neutrino mass over the next decade.
• Monday May 13: Julia Walter-Roszjár - "What is trickling down on us? A foray through meteoritics"

  Abstract: The research fields of meteorites and cosmochemistry are highly divers and interdisciplinary. The presentation will provide an overview about meteorite types and classes, their source bodies and regions, diverse mineralogy and characteristics of some selected meteorite types and related research projects. What can we find on Earth? What is the difference to terrestrial rocks? And what is the connection to astrophysics? Some aspects of the so-called micrometeorites and a conjunct scientific-artistic project to be installed at the Heldenplatz, Vienna will be highlighted in addition.
• Monday May 6: Cora Uhlemann - "Cosmology from the dark universe to galaxy surveys"

  Abstract: 

  In this talk, I will take you on a journey through our Universe across the largest scales and the longest times. We will look at the dark side of our Universe, dark matter and dark energy, that constitute 95% of today’s total energy budget. We will see a cosmic web of structure emerge from the tug of war between the gravitational pull of dark matter and the expansion driven by dark energy. As galaxies form within the skeleton of dark matter, we can use large galaxy surveys as a laboratory for fundamental physics. From this year, the Euclid space telescope and Rubin Legacy Survey of Space and Time will map the distribution of billions of galaxies across most of the sky and over 10 billion years of cosmic history. By identifying locations and shapes of galaxies, we can connect dark matter to galaxies and probe the rise of dark energy that determines the fate of our Universe. Analysing billions of galaxies across huge volumes is a big data challenge involving nonlinear physics, commonly tackled by only considering simple averages. I will describe how we can squeeze out more information by probing the cosmic large-scale structure beyond the average of standard forward models and statistical analyses.
• Monday April 22: Jorryt Matthee - "How galaxies and supermassive black holes changed the early Universe: insights after 1 year of JWST"

  Abstract: Identifying the first galaxies that emerged in the early Universe, characterising the properties of their stars and explaining the presence of supermassive black holes in galaxies at the highest redshifts are among the key goals of observational astrophysics. With its massive increase in imaging and spectroscopic capabilities in the infrared, the James Webb Space Telescope (JWST) is making significant progress in all these goals. In my talk, I will review lessons learned on galaxies in the early Universe after 1 year of JWST data. I will focus on the first spectroscopic census of emission-line galaxies in the EIGER survey of distant quasar fields, and the ALT survey of a powerful lensing cluster. These data informs us about the typical properties of stars, the chemical enrichment of the Universe, the halo masses and environments of the rarest quasars and show direct evidence that galaxies reionized the Universe. I will also discuss the surprising discovery of a population of faint active galactic nucleii (AGN) that may help us understand how the first supermassive black holes formed.
• Monday April 15: Roser Pello - "MOSAIC, a unique instrument for the ELT"

  Abstract: MOSAIC is the future multi-object fibre spectrograph for the ESO 39m Extremely Large Telescope (ELT), working in both the Visible and NIR domains. It is a first generation instrument, with unique capabilities in terms of multiplex, wavelength coverage and spectral resolution. While ELT first light instruments will be using only the central part of the ELT focal plane, MOSAIC is designed to cover the largest possible area (~40 arcmin²) thanks to an original stepped and tiled focal plane design which allows parallel observations in different modes. MOSAIC is optimized to achieve the best possible signal-to-noise ratio on the faintest sources, from our Galaxy to the epoch of the reionization. In this respect, it will be a privileged survey machine for the followup of sources being discovered by current and future major facilities, such as JWST, Euclid, ROMAN or SKA. I will review the main expected contributions of MOSAIC to extragalactic science, focusing on the study of the first galaxies formed in the Universe.
• Monday March 25: Giuseppina Battaglia - "The properties of satellite galaxies in the context of their orbits around the Milky Way"

  Abstract: The Local Group hosts about 100 dwarf galaxies, i.e. galaxies with stellar masses at least one order of magnitude lower than that of the Milky Way. As the smallest galaxies and the most dark matter dominated ones that we can observe in detail, Local Group dwarf galaxies are widely considered as precious systems to shed light on the processes that drive galaxy formation and evolution at small halo masses. Nonetheless, the majority of Local Group dwarf galaxies are found in the surrounding of a much larger system, i.e. the Milky Way or M31; this makes the knowledge of the orbits around the host a crucial piece of information for investigating the role of environment in shaping the dwarf galaxies' properties. In this talk I will present results from recent works, in which the exquisite astrometric data from the (early) third release of data from the ESA Gaia mission were used to provide probabilities of membership and systemic proper motions for Local Group dwarf galaxies. I will then discuss the orbital properties determined for the sub-set of about 50 dwarf galaxies found within 500 kpc from the Milky Way in the context of dwarf galaxies's group infall, tidal disruption from the Milky Way, and possible impact on the dwarfs star formation histories, as well as discuss some of the possibilities that clean samples of member stars from Gaia data are offering. Finally, I will briefly introduce the plans for the upcoming Galactic Archaelogy surveys with the WEAVE instrument, mounted at the prime focus of the William Herschel telescope.
• Monday March 18: Jarita Holbrook - "How Astrophysicists Discriminate"

   

  *** Note: this will take place at Lecture Hall 2, UZA II, Floor 1, 2A122 & via u:stream ***

  Special colloquium within the Faculty Public Lecture Series:

  "Academia and In/Equality"

  https://fgga.univie.ac.at/en/inequality/

   

  Abstract: Holbrook has been studying astrophysicists and astrophysics culture for over a decade, on top of having been educated as an astrophysicists before moving into the social sciences. In order to contextualize their experience in the field and to aid others in navigating the field, Holbrook studies astrophysicists practices of inclusion and exclusion. This presentation focuses on the myths of intellectual superiority, white entitlement, sexism and other forms of discrimination including anti-Black discrimination. Included are film clips of astrophysicists talking about these issues.

  Remote questions can be asked through the SRS system at this link:

  srs.univie.ac.at/p/07352090

   

   
• Monday March 18: Laura Magrini - "From Gaia-ESO to the next generation of high-resolution spectrographs"

  *** Note: Special Time 13:15 ***

  Abstract: Ground based specttroscopy is adding dimensionality to the astrometric,  photometric and spectroscopic data of the Gaia mission. Precise radial velocities, atomospheric parameters and abundances are enlarging our view of the Galaxy. Ingreasing the spectral resolution is improving our precision in measuring these quantities, but also is increasing the number of elements we can measure, tracing the history of the Galaxy with their different nucleosynthesis. Starting from a brief overview of some results obtained with the high resolution part of the Gaia-ESO survey, I will present two new facilities for the next decades focussed on high resolution spectroscopy, HRMOS -  a new spectrograph to be proposed for VLT- and WST - a new telescope fully dedicated to spectroscopy both MOS and IFS. 
• Monday March 11: Javier Oliveras - "Bayesian methods for the characterization of stellar systems in the solar neighborhood"

  Abstract: 

  Within the Bayesian paradigm,  the Bayesian hierarchical models offer a robust and practical solution to the two most difficult caveats of classical artificial intelligence methods: interpretability and uncertainty propagation.
  In this presentation, we will briefly review the formalism behind the Bayesian hierarchical models and some of the latest probabilistic programming frameworks used for model construction, inference, and criticism.
  We will see practical examples of Bayesian models for the characterization of stellar associations, star-forming regions and open clusters in the solar neighbourhood. These applications go from membership methodologies for the discovery of ultracool dwarfs, the identification of kinematic substructures, and the inference of population-level distribution such as spatial distribution, velocity dispersion, mass, age, and energy distributions.  
  Finally, we will see an example of a hybrid model that unifies a Bayesian hierarchical model with an artificial neural network, thus providing an interpretable and robust solution for the inference of stellar system ages through isochrone-fitting and Lithium depletion boundary techniques. These hybrid models are a powerful emergent tool that is worth exploring.

  Host: Núria Miret Roig
• Monday March 4th: Emily Hunt - "The star clusters of the Milky Way"

  Star clusters are the most useful places in the universe for studies of stellar and galactic evolution. Formed when stars collapse from the same molecular cloud into a cluster, star clusters offer a unique way to study stars of a homogeneous age and chemical composition across a range of masses. In the age of the Gaia satellite, the census of star clusters in our galaxy has exploded in size - but not without also presenting a number of challenges that require new machine-learning based techniques to solve.
  
  In this talk, I will present the work I conducted during my PhD, aiming to improve many aspects of the census of galactic star clusters in the age of Gaia. After an introduction to the field, I will start by discussing different unsupervised machine learning algorithms for detecting clusters in Gaia's billion-star dataset. Next, I will present our recently published catalogue of over 7000 clusters, which represents the largest homogeneous unduplicated catalogue of star clusters to date, including cluster classifications and parameters calculated with approximate Bayesian neural networks.
  
  Finally, I will discuss soon-to-be-published work on how bound and unbound star clusters can be better defined observationally, using their masses and Jacobi radii. I will present the largest ever catalogue of cluster masses and discuss many fascinating new results that come from this work, including: the first ever measurement of the global cluster mass function with Gaia data; the different lives of bound and unbound clusters; and how most clusters in the galaxy appear to have the same initial mass function - but only after first correcting for selection effects.
• Monday February 26: Francisco Nogueras Lara - "The Dark Heart of the Galaxy: A Tale of Stars and Dust"

  Abstract: The heart of the Milky Way is our nearest galactic nucleus and the only one where it is possible to resolve individual stars down to milli-parsec scales. Therefore, it is a unique template for understanding other galactic nuclei and their role in galaxy formation and evolution. The Galactic centre is also the most prolific star-forming environment in our Galaxy when averaged over volume, making it a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, high crowding and extinction hinder its study, and even its morphology and kinematics are not yet entirely clear. The recent publication of new photometric and proper motion catalogues has allowed us to gain new insights into its properties. In this talk, I will describe our recent results on its stellar population, formation scenario, and morphology.
  
  Host: Stefan Meingast
• Monday October 2: Philippe Bourdin - "The European Solar Telescope Project"

  Abstract:

  The EST project gives great opportunities for novel observations of the Sun at unprecedented and photon flux rates. This leads to better resolution and higher spectral capabilities when observing the lower atmospheric layers. We will discuss the current and future project phases, as well as the technical and scientific challenges.

  Host: Bodo Ziegler

   

   
• Monday October 9: Stella Offner - "Our Lonely Sun: How Multiple Star Systems Form (or don't)"

  Abstract: 

  Most stars are born with one or more stellar companions. Observational advances over the last decade have enabled high-resolution, interferometric studies of forming multiple systems and statistical surveys of multiplicity in star-forming regions. These have yielded new insights into how such systems form and how multiplicity affects disk evolution and planetary architectures. In this talk, I will review recent observational discoveries of the youngest multiple systems. I will present the results of star cluster simulations modeling the formation and evolution of multiple systems, and I will discuss the role of dynamics and environment in setting stellar multiplicity.  Finally, I will highlight remaining numerical and observational challenges.

  Host: Núria Miret Roig
• Monday October 16: Alyson Brooks - "Interpreting Newly Discovered Dwarf Galaxies"

  Abstract: 

  New observational surveys (e.g., Rubin's LSST, WALLABY) are enabling the discovery of hundreds of nearby dwarf galaxies.  Are we theoretically ready for what the surveys will find?  The past decade has seen tremendous progress in simulating realistic dwarf galaxies.  In this talk, I'll outline a campaign to simulate the largest suite of dwarf galaxies to date, in environments both near the Milky Way and further afield.  These high-resolution, cosmological simulations are probing dwarf galaxy formation from LMC-mass scales down into the regime of the ultra-faints for the first time.  I will highlight some of the first predictions at the low-mass edge of galaxy formation, and highlight the importance of realistic star formation when interpreting the dark matter content of dwarf galaxies.
  
  Host: Ryan Leaman
• Monday October 23: Chirag Modi - "Scaling simulation-based inference for the next generation of cosmological surveys"

  Abstract:
  Simulation-based inference (SBI) is a promising approach to leverage cosmological simulations and extract information from the non-Gaussian, non-linear scales that cannot be modeled analytically. However, scaling SBI to the volumes and resolutions probed by the next generation of galaxy clustering surveys can be computationally prohibitive.  This is exacerbated by the fact that if we do not use accurate high fidelity simulations, SBI is susceptible to model misspecification. I will begin by putting this in context with discussing the sensitivity of SBI on the various components of cosmological simulations: gravity model, halo-finder and the galaxy-halo distribution models (halo-occupation distribution, HOD). Then, to overcome this computational bottleneck, I will present a new framework for cosmological analysis called Hybrid simulation-based inference (HySBI). HySBI combines perturbative methods (PT) on large scales with conditional SBI on small scales, thus learning the small-scale likelihood for a wide range of statistics using only small-volume simulations and drastically reduces computational costs. As a proof-of-principle, I will show results of using HySBI to constrain cosmological parameters on dark matter density fields using both the power spectrum and wavelet coefficients, finding promising results that significantly outperform classical PT methods. Finally, I will discuss a roadmap for the next steps necessary to implement HySBI on actual survey data, including consideration of bias, systematics, and customized simulations.
  
  Host: Oliver Hahn
• Monday October 30: Paola Testa - "Observational signatures of coronal heating mechanisms in solar active regions"

  Abstract: 
  The details of the physical mechanisms responsible for heating the solar outer atmosphere to millions of degrees are still poorly understood. 
  Recent high resolution observations of the solar atmosphere (e.g., with SDO, Hinode, IRIS, SST) provide new powerful diagnostics of the coronal heating mechanisms. I will discuss how these new observations have enabled significant advances in our understanding of coronal heating properties in active regions. 
  I will especially focus on how high spatial, spectral, and temporal resolution coordinated observations of the chromosphere, transition region and corona, when coupled with state-of-the-art (1D/3D) models, can provide tight constraints on heating properties.
  
  
  Host: Manuel Guedel
• Monday November 6: John Tobin - "The cradles of star and planet formation: disks, multiplicity, and stellar masses of low to intermediate-mass protostars"

  Abstract:  

  The formation of disks and multiple star systems are integral parts of the star and planet formation process. Most stellar mass must be accreted through a disk, disks are the future sites of planet formation, and disks will also give rise to companion stars. Large surveys of protostars in the nearby star forming regions are being conducted (with resolutions as fine as 5 au) to characterize the disk radii, disk masses, disk structure, and the frequency of multiplicity throughout the protostellar phase. The measured multiplicity properties will be discussed, along links back to their formation mechanisms. Protostellar disks appear to be systematically more massive that the proto-planetary disks, but have substructure less frequently than proto-planetary disks. Protostar mass measurements are beginning to become available for many 10s of sources, enabling their measurements to be compared to predictions for mass functions. Thus, the combined results from surveys of protostars bring us closer to unlocking the physics driving various aspects of star and planet formation.
  
  Host: Alvaro Hacar
• Monday November 13: Sergio Torres Flores - "The role of galaxy interactions in compact groups of galaxies"

  Abstract:

  Compact groups of galaxies are associations of three to six galaxies, located in a very small volume, where the separation between them is of the order of the diameters of the galaxies. Given that, galaxy-galaxy interactions and mergers are a common phenomena in compact groups of galaxies, transforming these systems into ideal laboratories to study galaxy evolution. Indeed, these strong interaction events can transform the morphological, kinematical and physical properties of galaxies. In this context, in this talk I will present a morphological analysis developed for a sample of galaxies located in 340 compact groups. We found a peculiar galaxy population, which has a smaller effective radius than galaxies located in less dense environments, indicating that the environment is playing a relevant role in the evolution of galaxies in compact groups. In addition, I will present a MUSE analysis on the merging compact group HCG 31, where we found perturbed kinematics and perturbed metallicity distributions. Finally, I will present some recent results associated with a search for vertical perturbations in local galaxies, which are typically associated with galaxy-galaxy interactions events. Thanks to the use of 3D Fabry-perot data, we found vertical perturbations which are consistent with high resolution simulations.

  Host: Bodo Ziegler
• Monday November 27: Scott Lucchini - "Properties of the Magellanic Corona Model for the formation of the Magellanic Stream"

  Abstract: When viewing the Large and Small Magellanic Clouds (LMC, SMC) in HI 21-cm emission, we see much more than the galaxies themselves. The Magellanic Stream, a massive structure comprised of intertwined, multiphase, gaseous filaments, trails behind the Clouds covering over 200 degrees on the sky. While previous models of the Stream's formation have shown us that many of its properties can be reproduced through interactions between the Magellanic Clouds, two puzzles remain - the large amount of ionized gas associated with the Magellanic System, and the high mass of the LMC. To solve both these outstanding discrepancies simultaneously, we introduce the Magellanic Corona. This warm, ionized circumgalactic medium should surround the LMC as it interacts with the SMC and the Milky Way. Recent observations detecting the Magellanic Corona around the LMC today provide further evidence for a high LMC mass and this leads to strong implications for the history of the Magellanic Clouds. I will present simulations of the formation of the Magellanic Stream including the Magellanic Corona in which we are able to account for both the neutral and ionized components of the Stream while also reproducing the present-day positions and velocities of the LMC and the SMC in their motion around the Milky Way. Upon inclusion of the Magellanic Corona, we find a new family of orbital histories for the Clouds that result in the neutral Stream being significantly closer than previous models predicted. I will present these new models and discuss some of the many implications of this new paradigm for the Magellanic Stream.

  Host: Cameren Swiggum
• Monday December 4: John Peacock - "Galaxy formation in other universes"

  Abstract:

  The outstanding puzzle of fundamental cosmology is the cosmological constant: an effective vacuum density that is tiny by comparison with predictions based on quantum physics. In 1987, Steven Weinberg suggested that this puzzle might be resolved by observer selection: natural large values for the vacuum density would suppress cosmological structure formation, so there would be no star formation in galaxies, and hence no observers. I will describe recent attempts to investigate this idea in detail, taking hydrodynamical simulation codes that succeed in modelling galaxy formation in our observed universe, and applying them to cosmologies with much larger cosmological constants. I will also contrast the simulation results with the predictions of a simplified analytic model for cosmic star formation. Different approaches to this problem yield somewhat different answers, but are in qualitative agreement: raising the cosmological constant does reduce the global efficiency of star formation, meaning that such models are less likely to be experienced by observers. But this suppression is relatively slow, so that cosmological constants more than 10 times the observed value would still form stars efficiently. Thus our observed universe has a vacuum density that is small compared with the value that would be typical in Weinberg’s model, and the question is whether this could be a statistical fluctuation that is not too rare.

  Host: Oliver Hahn
• Monday December 11: Claudia Paladini - "Stellar surfaces through the looking-glass"

   

  Abstract: 

  Stellar convection plays an important role in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars. A direct characterization of convective structures in terms of size, contrast, and life-span is quite challenging because stars are still pretty far and convective patterns are small. Most of our knowledge about stellar convection comes from studying the Sun. On the surface of our star a couple of millions of convective cells are observed, each one with a size of about 2000 km.Following predictions dating back to the ’70, the surface of evolved stars (or a Sun at later evolutionary stage) is expected to be populated by only a few large convective cells several tens of thousand times the size of the solar ones. Such predictions were confirmed at the end of last decade  by direct observations of the stellar surface of the low mass Asymptotic Giant Branch Stars pi1 Gruis. More recently the models are being challenged when it comes to more massive objects like the Red Supergiants. In this talk I will review the recent results obtained using high angular resolution techniques to resolve the surface of stars, and I will discuss the various scenarios used to interpret the images. Are we really looking at convection? 

  Host: Josef Hron