Seminars and Colloquia at ESO Garching and on the campus

July 2024

25/07/24 (Thursday)
10:00, Library (ESO HQ, Garching) | ESO Garching
ESO Galaxy Evolution Coffee
Talk — The star formation efficiency and physical conditions of the ISM in galaxies from the local and early Universe
Vicente Villanueva (Universidad de Concepción)
11:00, USM, Scheinerstr. 1, Munich | ESO Garching
LMU Astrophysics Seminar
Talk — Do we need to look beyond Cold Dark Matter?
Prof. Andrea Macciò (NYU Abu Dhabi)
11:00, MPA Large Seminar Room E.0.11 (MPA, Garching) | ESO Garching
Cosmology Lectures
Talk — Postdoc/Staff Lecture Series on Cosmology
Julia Stadler (MPA)
30/07/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Satellite Signatures in the Multiphase Halo Gas with the IllustrisTNG and TNG-Cluster simulations
Eric Rohr (MPIA, Heidelberg)

Abstract

Using the IllustrisTNG and TNG-Cluster simulations, I quantify the impact of satellite galaxies on the host halo gas as functions of satellite stellar mass, host halo mass, and cosmic time. Before infall, satellite galaxies were still central galaxies with their own multiphase CGM and ISM, undergoing feedback from star-formation and/or SMBHs. As they fall into other larger hosts, ranging from MW-like galaxies to the largest clusters in the Universe, both their CGM and ISM are redistributed due to both internal feedback processes and external environmental effects, such as ram pressure stripping. Namely, satellites deposit their own gaseous reservoirs into the host halos, contributing to both the cool and hot gas in their host CGM. In particular, I follow the evolution of ~500 jellyfish galaxies in TNG50 as they deposit their cool, metal-enriched ISM into their host halos. Meanwhile, some massive cluster satellites in TNG-Cluster are able to retain their own CGM, contributing to the overall soft X-ray flux in the intracluster medium (ICM). Further, I show that the ICM today is multiphase, where clusters tend to have ~10^9-10 Msun of cool gas in their halos, according to TNG-Cluster. In the past, however, these ~350 cluster progenitors had ~10^10.5-11 Msun of cold gas, which yields observable predictions. The evolution of the cool ICM since z <~ 4, which holds for lower mass halos as well, is a complex interplay between new cool gas sources and sinks, including accretion from large scale filaments, satellite stripping, gas cooling, and gas heating via AGN feedback and virial shocks. Lastly, I discuss in-situ ICM star-formation and potential Halpha emission therefrom, and compare the MgII column density profiles in TNG-Cluster to recent SDSS stacks, where TNG-Cluster naturally produces a signficant amount of MgII absorbers.

September 2024

03/09/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — New proper motion catalog reveals fast-moving stars around an intermediate-mass black hole in Omega Centauri
Maximilian Haeberle (Max Planck Institute for Astronomy Heidelberg)

Abstract

The intermediate-mass black hole (IMBH) regime is still poorly constrained, with few detections between 150 and 10^5 Msun. This poses a challenge to our understanding of supermassive black hole formation in the early universe.
An IMBH in ω Centauri, the Milky Way’s most massive globular cluster, has been suspected for almost two decades, but all previous detections have been questioned due to their assumptions and the possible mass contribution of a central cluster of stellar mass black holes.
I will present a new astrometric catalog for the inner region of ω Centauri, containing 1.4 million proper motion measurements based on 20 years of Hubble Space Telescope observations.
Our catalog is supplemented with precise HST photometry in 7 filters, allowing the separation of its complex subpopulations. The catalog is publicly available, providing the largest kinematic dataset for any star cluster.
Our new catalog revealed 7 fast-moving stars in the innermost 3 arcseconds (0.08 pc) of ω Centauri. The inferred velocities of these stars are significantly higher than the expected central escape velocity of the star cluster, so their presence can only be explained by being bound to an IMBH. From the velocities, we can infer a firm lower limit of the black hole mass of ∼8,200 Msun. In addition, we compare the full distribution of stellar velocities to N-Body models that suggest the presence of an IMBH with M≲50,000 Msun. These results confirm ω Centauri hosts an IMBH which makes this the nearest known massive black hole and, after the Milky Way center, only the second where we can track the orbits of multiple individual bound companions.

10/09/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Constraining the IMF slope with galaxy chemical evolution for both high- and low-mass stars
Yan Zhiqiang (Nanjing University of Science and Technology)

Abstract

The element compositions of resolved stars formed at distinct epochs record the chemical evolution trajectory of a galaxy. As this evolution is influenced by the galaxy-wide stellar initial mass function (gwIMF), the abundance profiles of stars offer a means to estimate the gwIMF. In this presentation, I will demonstrate the application of this methodology using the dwarf galaxy Sculptor as a case study. Specifically, I will elucidate how the gwIMF of long-lived low-mass stars intricately shapes the observed stellar metallicity distribution of a galaxy, thereby allowing for the estimation of low-mass gwIMF via galaxy chemical evolution modeling. Our analysis suggests that dwarf galaxies, characterized by low stellar metallicities and a low star formation rates, exhibits a shallower gwIMF slope for low-mass stars and a steeper gwIMF slope for massive stars (bottom- and top-light IMF). Furthermore, we have compared our findings with those derived from independent IMF estimation techniques including stellar population synthesis and star counting, illustrating a coherent and systematic IMF variation.

17/09/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Miren Munoz Echeverria (IRAP - Institut de Recherche en Astrophysique et Planétologie)
24/09/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Robert Klement (ESO, Chile)

October 2024

01/10/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Stéphane Blondin (Laboratoire d'Astrophysique de Marseille)
08/10/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Joshiwa van Marrewijk (Leiden University)
10/10/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Irene Tamborra (Niels Bohr Institute, University of Copenhagen)
15/10/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Fatemehzahra Majidi (Blue Skies Space)
22/10/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Cold clouds in the circumgalactic media of simulated Milky Way-like galaxies
Rahul Ramesh (University of Heidelberg)

Abstract

I will present recent and ongoing explorations regarding cold clouds in the circumgalactic media of (simulated) z=0 Milky Way-like galaxies. We find that these CGMs are typically filled with >~100s-1000s of such cold gas structures, possibly analogs of high-velocity clouds (HVCs) observed in the Milky Way sky. These objects primarily originate as a result of cold gas outflows from the central galaxy and/or precipitation of the warm-hot phase of the CGM. Clouds arising as a result of stripping of cold gas from satellites are rare in our sample (<5%). Lastly, we find that properties of clouds are diverse, and may furthermore depend closely on their source of origin.

29/10/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Discs & Exoplanets in Multiple Stellar Systems
Nicolás Cuello (Institut de Planétologie et d’Astrophysique de Grenoble (IPAG))

Abstract

Stellar multiplicity is ubiquitous at early stages of star formation. This unavoidably modifies the initial conditions of protoplanetary discs and hence planet formation. The high level of stellar multiplicity translates into a high number of binaries and triple stellar systems in active star forming regions. In this lunch talk, we will briefly cover disc dynamics within multiple stellar systems, mainly binaries and triples. In addition, based on numerical simulations, we will discuss how to interpret complex disc morphologies such as spirals, warps, and streamers as signposts of ongoing gravitational interaction between young stars. We will illustrate these claims with representative examples of observed multiple stellar systems with discs (e.g. ALMA, VLT, GRAVITY, Gaia). To conclude, we will briefly discuss the current open question regarding planet formation in multiple stellar systems given the emergence of planetary architectures in such systems.

November 2024

19/11/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Padelis Papadopoulos (University of Thessaloniki)

January 2025

16/01/25 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Laura V. Sales (University of California Riverside)