Upcoming Seminars
Seminars are typically held every second Thursday at 11am, preceded by coffee & cookies at 10:30am
| Date & Time | Speaker | Title & Abstract | Location |
| 18.12.2025 11:00am (coffee & cookies 10:30am) | Fergus Cullen (University of Edinburgh) | Title: Chemical enrichment and dust build-up at early cosmic epochs with JWST Abstract: One of the transformative contributions of JWST has been to enable detailed studies of chemical enrichment and dust formation in the earliest galaxies. In this talk, I will present new observational results tracing the emergence of metals and dust during the first billion years of cosmic time. Drawing from the broader literature, but with a focus on results from the JWST-EXCELS survey, I will discuss key insights emerging from the rapidly growing samples of direct metallicity measurements at high redshift. These observations reveal evidence for deviations from the local baryon cycle equilibrium at early epochs, demonstrate the power of multi-element abundance analysis for constraining enrichment timescales, and have begun to identify extremely metal-poor systems with signatures of unique stellar populations. I will also new present constraints on dust build-up at z > 9 from JWST wide-area imaging surveys, exploring how these complement existing ALMA constraints and help to explain the large number of UV-bright galaxies at z > 10. Together, these results are reshaping our understanding of how the first generations of stars being to enrich the Universe. Host: Jorryt Matthee | Moonstone Seminar Room E |
| 15.01.2026 11:00am (coffee & cookies 10:30am) | Michele Ginolfi (University of Florence) | Title: TBD Abstract: TBD Host: Claudia di Cesare | Moonstone Seminar Room F |
| 29.01.2026 11:00am (coffee & cookies 10:30am) | Krista Smith (Texas A&M University) | Title: TBD Abstract: TBD Host: Mark Avara | Moonstone Seminar Room E |
| 12.02.2026 11:00am (coffee & cookies 10:30am) | Charlotte Mason (University of Copenhagen) | Title: TBD Abstract: TBD Host: Sara Mascia | Sunstone Seminar Room A |
| 26.02.2026 11:00am (coffee & cookies 10:30am) | Nicholas Rui (Princeton University) | Title: TBD Abstract: TBD Host: Ylva Götberg | Foyer seminar room in Office Building West |
| 12.03.2026 11:00am (coffee & cookies 10:30am) | Tamara Bogdanovic (Georgia Institute of Technology) | Title: TBD Abstract: TBD Host: Zoltan Haiman | Moonstone Seminar Room E |
| 26.03.2026 11:00am (coffee & cookies 10:30am) | Wenbin Lu (University of California, Berkeley) | Title: TBD Abstract: TBD Host: Ilaria Caiazzo | Moonstone Seminar Room E |
| 09.04.2026 11:00am (coffee & cookies 10:30am) | Konstanze Zwintz (University of Innsbruck) | Title: TBD Abstract: TBD Host: Lukas Einramhof & Nicolas Muntean | Moonstone Seminar Room E |
| 23.04.2026 11:00am (coffee & cookies 10:30am) | Francesco Ferraro (University of Bologna) | Title: TBD Abstract: TBD Host: Ilaria Caiazzo | Foyer seminar room in Office Building West |
| 21.05.2026 11:00am (coffee & cookies 10:30am) | Alberto Sesana (University of Milano-Bicocca) | Title: TBD Abstract: TBD Host: Zoltan Haiman | Moonstone Seminar Room E |
| 25.06.2026 11:00am (coffee & cookies 10:30am) | Sylvia Ploeckinger (University of Vienna) | Title: TBD Abstract: TBD Host: Gauri Kotiwale | TBD |
Past Seminars
| Date & Time | Speaker | Title | Location |
| 04.12.2025 11:00am (coffee & cookies 10:30am) | Tereza Jeřábková (Masaryk University, Brno) | Title: Bridging Cosmic Scales: Understanding Star Formation from Molecular Clouds to Galaxies Abstract: How and what stars form is a fundamental question in astrophysics, influencing the cosmic baryonic cycle, chemical enrichment, and the evolution of galaxies from early epochs to the present day. Despite decades of research, key questions about star formation remain open: What are its initial conditions? Do stars form similarly across different environments, from the Milky Way to high-redshift galaxies? How do dynamical processes in star clusters shape the stellar populations we observe in galaxies today? In my research group, we address these questions by embracing the multi-scale nature of star formation, combining observational, theoretical, and computational approaches. Using data from Gaia, ESO/VLT, and upcoming 4MOST surveys, we investigate resolved star-forming regions and star clusters, employing advanced techniques such as unsupervised machine learning and state-of-the-art N-body simulations (PeTaR).Beyond resolved studies, we aim to bridge star formation physics with galaxy-scale stellar populations. By leveraging the GalIMF code – an innovative semi-empirical model linking individual star-forming regions to galactic stellar populations – we explore how star formation conditions translate into observable properties of galaxies and their chemical evolution. This approach also enables synergies with hydro/cosmological simulations, addressing resolution limitations and connecting theoretical star formation studies with large-scale structure formation. As my research group takes shape, I aim to foster interdisciplinary collaborations across the department, from stellar evolution and resolved stellar populations to galaxy formation and cosmology. This work not only enhances our understanding of how stars form and evolve but also contributes to a broader framework connecting astrophysical processes across cosmic scales. Host: Jorryt Matthee & Gauri Kotiwale | Mondi 2a, Central Building |
| MONDAY 01.12.2025 11:30am (Reception at 11:00am) | Chiara Mingarelli (Yale University, USA) Dr. Chiara Mingarelli is an Assistant Professor of Physics at Yale University and a prominent researcher in the field of gravitational wave astrophysics. Her work focuses on using pulsar timing arrays to detect nanohertz-frequency gravitational waves, particularly those generated by supermassive black hole binaries. She has held key leadership roles, including serving on NASA’s Physics of the Cosmos Executive Committee and co-chairing the Gravitational Wave Science Interest Group. Dr. Mingarelli is also a Full Member of the NANOGrav collaboration, contributing to the discovery of the gravitational wave background. An advocate for diversity in science, she previously served as the Ada Lovelace Director of Diversity at the Flatiron Institute. Dr. Mingarelli has been widely recognized for her contributions, with over 100 refereed papers with 16,000 citations, and numerous grants from NASA and the National Science Foundation. https://www.chiaramingarelli.com | — INSTITUTE COLLOQUIUM — Title: Targeted searches for supermassive black hole binaries Abstract: Pulsar timing arrays have opened a new observational window onto nanohertz gravitational waves, providing evidence for a gravitational wave background and motivating the search for the individual supermassive black hole binaries that generate it. In this talk, I will present the first catalog of electromagnetically informed targeted searches using the NANOGrav 15 year data set, focusing on 114 active galactic nuclei with observed periodicity or other indications of binarity. By incorporating source specific information such as sky position, distance, redshift, and an estimated gravitational wave frequency, our limits on strain and chirp mass are improved on average 2.6x compared to all sky analyses. I will describe the methodological framework that enables these gains, summarize the catalog level results, and discuss how these searches connect to population models, electromagnetic follow-up, and current measurements of the gravitational wave background. The tests outlined here create a path toward the first detection of an individual supermassive black hole binary with pulsar timing arrays. Host: Zoltán Haiman | Raiffeisen Lecture Hall |
| 20.11.2025 11:00am (coffee & cookies 10:30am) | Oliver Hahn (University of Vienna) | Title: How to fit a cosmological simulation to the Universe Abstract: The large-scale structure of the Universe—the distribution of galaxies, clusters, and intergalactic gas across cosmic scales—offers a powerful window into fundamental physics. Modern surveys are collecting unprecedented volumes of high-quality data from ground- and space-based observatories. To extract maximum scientific value from these observations, we need analysis methods that preserve as much information as possible and can reveal unexpected physics. Traditional approaches compress observations into summary statistics before comparing them to theory, inevitably discarding information. Recent advances now allow us to perform “field-level inference”: fitting complete cosmological simulations directly to the full data. I will introduce the key concepts behind this approach and present the framework the Vienna cosmology group is developing to apply these techniques to next-generation surveys. Host: Zoltán Haiman | Moonstone Seminar Room E |
| 06.11.2025 | Kishalay De (Columbia University, New York) | Title: Dust enshrouded eruptions from planets to supermassive black holes Abstract: Eruptive mass loss and the resulting dramatic brightness variations are ubiquitous in the lives of stars, their planetary companions, and their remnants. While these episodes can fundamentally change their evolutionary course, they frequently enshroud them in veils of dust and make them unobservable in the optical, ultraviolet and X-ray bands. In this talk, I will present our efforts toward conducting an all-sky survey of infrared variability, aimed at capturing these poorly observed phases in stellar evolution. I will introduce the WISE Transients Project (WTP), an initiative aimed at an end-to-end exploration of the variable mid-infrared sky using archival data from the NEOWISE sky survey. Reprocessed using state-of-the-art image processing techniques, the NEOWISE data have been repurposed to serve as a transient discovery engine, providing fundamental new insights ranging from the co-evolution of stars and planets to the formation of black holes. I will conclude with an overview of the coming decade of infrared surveys, highlighting i) the potential of the recently launched SPHEREx mission to provide an unbiased spectral atlas of IR transients, ii) the rise of ground-based IR survey capabilities spearheaded by novel instrumentation and iii) the first look into the high redshift dusty universe with the Roman space telescope. Host: Ilaria Caiazzo | Mondi 3, Central Building |
| 23.10.2025 | Kaustubh Hakim (KU Leuven and Royal Observatory of Belgium) | Title: Chemical Composition of Sub-Neptunes from a Multi-Disciplinary Approach Abstract: Sub-Neptunes are one of the two most common types of exoplanets in the galaxy with no solar system analogues. The ubiquity of these planets poses fundamental questions on planet formation. Without good constraints on the chemical composition of their atmospheres and interiors, such questions cannot be comprehensively answered. Sub-Neptune atmospheres are being characterised by the James Webb Space Telescope (JWST), yet ambiguities remain about chemical makeup. I will address why a multi-disciplinary approach combining modelling efforts with ab initio and laboratory experiments is a way forward to develop a better understanding of this common exoplanet type. I will also highlight how currently active and upcoming space and ground-based telescopes, including PLATO, ARIEL, ELT, and MARVEL, enable the holistic understanding of these exoplanets. Host: Ylva Götberg | Foyer seminar room in Office Building West |
| 16.10.2025 | Santiago Torres (ISTA) | Title: Tracing Planetary Systems Dynamics Across Stellar Lifetimes Abstract: How planetary systems form and evolve around their host stars remains one of the most compelling yet unresolved questions in modern astrophysics. Recent observations continue to challenge existing theories, from the discovery of Hot Jupiters and their exomoons, to the diverse planetary architectures observed in young stellar systems, and the existence of planets around evolved stars. In order to interpret these observations and bridge the gap in our understanding of planetary system evolution, it is essential to advance theoretical and numerical models capable of linking their formation and evolution across the full stellar lifecycle. To build such models, we must consider not only the internal dynamics of planetary systems and the evolution of their host star, but also the influence of their birth environments. Because, planetary systems are not born in isolation, they form in stellar clusters where encounters with nearby stars leave long-lasting dynamical imprints. These early interactions shape the distribution of planets and small bodies, influencing their later evolution as the host star evolves and eventually becomes a white dwarf. In this talk, I will first present my recent results on the dynamical evolution of planetary systems and debris disks under the combined influence of planets and stellar encounters within open clusters. These simulations reveal how planetary systems are shaped by their birth environments, leading to the formation of extended minor-body reservoirs such as Kuiper belts and Oort clouds, and even creating intercluster and interstellar objects. Building on these architectures, I will then discuss how such systems are later disrupted and reshaped as their host stars evolve into white dwarfs. Host: Ilaria Caiazzo | Foyer seminar room in Office Building West |
| 25.09.2025 | Title: Our Universe in Simulation Abstract: Ongoing and upcoming cosmological surveys—including the Simons Observatory, LiteBIRD, CMB-S4, Rubin LSST, Euclid, DESI, PSF, SPHEREx, and the Roman Space Telescope—will deliver observations of unprecedented precision. Joint analyses across these surveys will be essential for uncovering fundamental physics, including the nature of inflation, dark energy, dark matter, neutrino mass, and more. In this talk, I will discuss the opportunities, challenges, and strategies for simulating our universe across multiple wavelengths to realize these goals. Host: Zoltán Haiman | Moonstone Seminar Room E | |
| 03.07.2025 | Leila Calcaferro (La Plata, Argentina) | Title: Asteroseismology of White Dwarfs: Probing the Final Stages of Stellar Evolution Abstract: White dwarfs are the evolutionary endpoints of most stars in the Universe. Their study provides key insights into stellar formation and evolution, as well as the history of our Galaxy. Some white dwarfs exhibit nonradial pulsations, which can be analyzed through asteroseismology, a powerful technique that compares observed pulsation periods with theoretical models. This method yields valuable information about their origin, internal structure, and evolutionary history. It also allows us to infer key properties such as stellar mass, effective temperature, surface gravity, and even internal rotation. In this talk, I will present recent results from our ongoing efforts to characterize pulsating white dwarfs, with an emphasis on low- and extremely low-mass ones. | Heinzel Seminar Room, Office Building West |
| 26.06.2025 | Imre Bartos (U Florida, USA) | Title: Shifting paradigms in Gravitational-wave Astrophysics Abstract: The decade since the first detection of gravitational waves brought about several transformational discoveries. The LIGO and Virgo observatories detected more and heavier black holes than anticipated; the first multi-messenger detection of colliding neutron stars provided invaluable insights on the production of the heaviest elements in the universe; and a particularly heavy black hole was discovered that could have not come from stellar core collapse. With the exponentially increasing rate of discoveries over the next decade and a half, gravitational waves are all but guaranteed to lead to further shifts in our astrophysical paradigm. After introducing how we got here, I will primarily focus on one of these shifting paradigms: the collision of black holes that was historically considered to be “dark” events producing only gravitational waves, but new observations point towards a brighter, more impactful, multimessenger picture. | Heinzel Seminar Room, Office Building West |
| 05.06.2025 | Paul Beck (U La Laguna, Spain) | Title: Tales of stellar and binary co-evolution, told by solar-like oscillations Abstract: Understanding stellar structure and evolution significantly impacts our understanding of the tight-knit evolution of galaxies and exoplanet systems. However, hidden behind the luminous layers of the stellar atmosphere, the deep interior of a star is eluding from direct measurements. The seismic study of waves propagating the deep interior provides the only way to measure the internal structure, dynamics, and mixing in any given star and compare it to theoretical models. With the advent of high-precision photometric data from space missions like NASA’s Kepler, a golden age of asteroseismology has begun. Seismic studies of thousands of solar-like oscillators have led to major breakthroughs in our understanding of red-giant stars, including the detection of core seismic signatures and internal rotation profiles. These insights have significantly advanced our knowledge of stellar evolution in its more advanced phases. When combined with complementary diagnostic, such as binarity, tidal interactions, surface rotation, and lithium abundances, asteroseismology provides a powerful framework to probe complex internal processes and model assumptions. In this talk, we explore how stellar oscillations, combined with binary dynamics, allow us to trace changes in orbital period, eccentricity, and stellar activity driven by evolution and tidal interactions. We show how asteroseismology reveals the impact of star-star interactions on activity and stellar cannibalism. However, the lack of solar-like oscillators in eclipsing binaries limits our ability to calibrate models. We highlight how data from ESA’s Gaia and the upcoming PLATO mission will address this gap, offering benchmark systems to improve seismic scaling relations and stellar evolution models. | Moonstone Seminar Room E |
| 22.05.2025 | Hannah Übler (MPE, Garching, Germany) | Title: Observational constraints on massive black holes in the first billion years Abstract: One of the most surprising results coming out of the first years of science operations with JWST is the unexpectedly high abundance of actively accreting black holes in the early Universe. Compared to the local population, many of these early black holes appear to differ in various aspects, such as their relation to their host galaxies or their multi-wavelength properties. These observational findings challenge our understanding of the past evolution of present-day supermassive black holes, and provide new ways to constrain theoretical models of black hole formation and growth. I will give an overview of recent observational results on massive black holes in the first few billion years, driven by the unprecedented capabilities of JWST to explore cosmic dawn, and with a focus on results from the NIRSpec GTO surveys JADES and GA-NIFS, and the GO Large Program BlackTHUNDER. | Raffeisen Hall, main building |
| 15.05.2025 | Sara Rastello (U Barcelona, Spain) | Title: Star–Black Hole Interactions in Young Star Clusters Abstract: In dense star clusters, close encounters between stars and compact objects—such as stellar-mass black holes or neutron stars—can lead to a wide range of outcomes, from the disruption of stars to the formation of quiescent binary systems, like those recently discovered thanks to Gaia. The former are transient events known as micro–tidal disruption events(micro-TDEs). In this contribution, I will explore the dynamical origin of micro-TDEs in young star clusters (YSCs). I have carried out a suite of high-precision direct N-body simulations of massive, collisional YSCs using the state-of-the-art code PeTar. I will present results on the population of micro-TDEs formed in YSCs through hyperbolic or parabolic encounters between single stars and black holes, as well as interactions involving binary compact objects. Although micro-TDEs have not yet been observed, they represent promising multi-messenger sources. I will discuss their potential relevance both as sources of gravitational waves and as electromagnetic transients, possibly detectable with upcoming surveys or instruments (i.e. LSST, LGWA). | Moonstone Seminar Room E |
| 24.04.2025 | Ingrid Pelisoli (U Warwick, UK) | Title: Fantastic binaries and how to find them Abstract: A large fraction of stars are in binary systems, and yet our understanding of how binarity affects stellar evolution is still fragmentary and only qualitative in many aspects. From gravitational waves to supernova Ia explosions, binary interaction plays a crucial role in our comprehension of the Universe. To improve our modelling of the many pathways of binary evolution, observational input is required. In this talk, I will describe binary interaction and its observational signatures, present recent advances in the characterisation of evolved binary systems containing white dwarfs, and discuss the impact of these discoveries on our understanding of supernova Ia progenitors. | Moonstone Seminar Room E |
| 10.04.2025 | Przemek Mròz (U Warzaw, Poland) | Title: Toward the mass function of isolated black holes with modern observations of microlensing events Abstract: Gravitational-wave detectors – LIGO, Virgo, and KAGRA – have revealed a population of massive black holes whose origin is still a subject of vigorous debate. Understanding the population of black holes in the Milky Way is, therefore, key to understanding and putting into the astrophysical context the LIGO/Virgo/KAGRA discoveries. Gravitational microlensing remains the only viable technique that enables us to detect and directly measure masses of isolated stellar remnants, especially neutron stars and black holes. In this talk, I will present the recent advancements in the field of gravitational microlensing, which have led to the discovery of the first isolated stellar-mass black hole in the Milky Way and which will pave the way for future similar discoveries. I will discuss how astrometric and interferometric observations of gravitational microlensing events allow us to detect and characterize isolated neutron stars and black holes. Finally, I will discuss whether black holes of different sizes can make up dark matter. | Heinzel seminar room, Office building west |
| 03.03.2025 | Gergö Popping (ESO, Garching, Germany) | Title: Revealing the dust and cold gas properties of galaxies at cosmic noon with ALMA Abstract: At the peak epoch of cosmic star formation activity, cosmic noon (z~2), the molecular gas density of the Universe was an order of magnitude higher than today and the largest fraction of star-formation took place in dust-obscured environments. These observations show that dust and cold gas are ubiquitous in the interstellar medium (ISM) of high-redshift galaxies and plays a key role in galaxy physics. In the last decade ALMA has played a key role in characterising the dust and cold gas properties of galaxies at cosmic noon, providing new insights in the dust and gas content and morphological properties of massive star-forming galaxies. The coming decade will see the technological advances to push these studies towards less massive objects that were responsible for the bulk of star-formation in the Universe. Furthermore, it is expected that in the coming years the detailed distribution of dust and molecular gas emission in galaxies across cosmic time will be observed on a systematic basis. In this talk I will highlight our theoretical and observational efforts to start characterising the dust and cold gas properties of normal galaxies at cosmic noon, not limited to the most massive and actively star-forming galaxies. I will focus on the relative dust content of low-metallicity galaxies and how these constrain galaxy formation models, as well as our predictions for the distribution of CO and dust-continuum emission in galaxies over cosmic time and how stacking observations can already provide us a glimpse of the future possibilities. I will finish by discussing the implications of our results for the interpretation of current and future ALMA and JWST observations. | Moonstone Seminar Room E |
| 12.12.2024 | Iair Arcavi (Tel Aviv University, Israel) | Title: Stars Disrupted, Destroyed and Coalesced Abstract: Supernovae, tidal disruption events and merging neutron stars can provide a wealth of physical insights from nuclear physics to cosmology; they can teach us about the creation of the elements, the formation of compact objects, accretion processes, feedback, galaxy evolution, and more. I will present how my research group is investigating the nature of tidal disruption events, their surprising emission properties and puzzling host-galaxy preference; and how we are using supernovae to constrain late-stage stellar evolution and explosion of massive stars, and asteroseismology to constrain their inner structure. If time allows I will also mention how we are hoping to find more gravitational-wave counterparts through multi-observatory coordination, and why we wish to do so. | Mondi 1, Main building |
| 05.12.2024 | Piyush Sharda (U Leiden, The Netherlands) | Title: Population III star formation Abstract: Population III stars were the first stars that formed in the Universe, a mere 300 million years after the Big Bang. These stars produced the first supernovae and black holes, enriched the interstellar medium (ISM) with metals, were the building blocks of the first galaxies, and significantly contributed to cosmic reionization. However, no Population III stars have ever been observed, earning them the title of Holy Grail of stellar astrophysics. Compared to star formation and feedback in metal-rich environments today, the lack of direct observations at low metallicities has posed a significant challenge for understanding the physics behind their formation and evolution. In this talk, I will introduce POPSICLE, a new framework for high resolution simulations that can cater to star formation and feedback in low metallicity environments reminiscent of redshift > 10 galaxies as well as metal-poor dwarf galaxies at redshift zero. I will describe how incorporating the full spectrum of ISM physics coupled to stellar evolution is crucial to constrain the stellar initial mass function (IMF) and feedback in such environments. I will particularly focus on Population III stars, and discuss the interplay between different physical mechanisms that sets their masses, and their role in feedback and black hole growth in the early Universe. I will conclude by showcasing the capability of GPU-accelerated simulations to revolutionize our understanding of the astrophysics of cosmic dawn, and bring theory at par with state of the art observations from JWST and the ELT. | Ballroom, Main building |
| 21.07.2024 | Valeriya Korol (MPA Garching, Germany) | Title: Galactic Palaeontology with LISA Abstract: The Milky Way, while extensively studied, still conceals much about its population of stellar remnants, including white dwarfs, neutron stars, and black holes, as these objects often remain undetectable by electromagnetic telescopes. Yet, their detection and study become feasible when they form ultra-short period binaries, thus becoming detectable via gravitational wave radiation. In my talk, I will showcase the potential of the upcoming Laser Interferometer Space Antenna (LISA) data for Galactic studies, emphasising its ability to characterise ultra-short period binary populations across the entire Milky Way. I will outline how the LISA mission could contribute to solving some of the persistent questions in our field, such as the progenitors of Type Ia supernovae. | Moonstone Seminar Room E |
| 07.11.2024 11:00am | Emeline Bolmont (University of Geneva, Switzerland) | Title: Exploring Planetary Habitability Abstract: In this talk, I will present the research done in my group on the evolution and habitability of planets, particularly those orbiting low-mass stars such as Proxima Centauri b and the TRAPPIST-1 system. These planets are not only positioned within or near the habitable zone but are also subject to tidal evolution due to their close proximity to their host stars. I will mention in this talk two areas of our work: – Tidal Evolution and habitability of Planets: I will discuss advancements in modeling tidal interactions, emphasizing the importance of considering proper responses for rocky planets. I’ll share our recent work on the rotation of the TRAPPIST-1 planets and how this can impact the climate of the planets. – Earth-Life in Extraterrestrial Environments: Building on interdisciplinary discussions at the Centre pour la Vie dans l’Univers (CVU), we are investigating the resilience of Earth-based life forms under extraterrestrial conditions. Through simulations and lab experiments, we aim to understand how life could survive and adapt on other planets, with a focus on early Mars. Together, these aspects provide a comprehensive view of how we can assess the potential of small temperate planets for hosting life, contributing to our understanding of habitability in the universe. | Foyer Seminar room, Office building west |