Seminars and Colloquia at ESO Garching and on the campus

April 2024

03/04/24 (Wednesday)
10:00, Library (ESO HQ, Garching) | ESO Garching
Informal Discussion
Talk — Three's a party: the three disks of Be binary systems
Amanda Rubio (ESO)

Abstract

Accretion disks are common in astrophysical systems, from AGN to protostellar disks. The disks of Be stars (rapidly rotating Main Sequence B-type stars) are special: they are discretion disks, built from matter ejected by the central object. When in a binary system, the companion can affect the Be disk in many ways, exciting density waves and even causing truncation. It can also accrete material from it, as is the case for Be X-ray binaries, whose X-ray emission is powered by accretion onto a compact companion. In our work we simulate Be binaries with a smoothed particle hydrodynamics (SPH) code (Okazaki et al. 2002) in order to investigate the effects of the companion on the dynamics of the disk, the process through which it accretes matter, and how the system loses mass as whole. We employ a modified version of the code, specially updated by us to increase resolution in low density areas of the system, such as the outer disk and around the companion. We find that disks are formed around the secondary in all models, but viscosity, mass ratio and period play a significant role in their structure and kinematics. A circumbinary disk is formed around the system for all simulations, which was never before seen in simulations for coplanar, circular Be binaries, but agrees with recent observational findings of radio emission from these types of system, where an ad-hoc circumbinary disk model was employed. Our study paves the way for a better understanding of X-ray emission in Be X-ray binaries, and offers an insight in how hidden companions of Be stars can be detected observationally.

09/04/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Matthew Kenworthy (Leiden Observatory)
11/04/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Exploring SMBH-Galaxy Coevolution with GRAVITY+
Taro Shimizu (MPE)

Abstract

Near-infrared interferometry is a unique tool to study the inner sub-parsec structure of AGN which is inaccessible with current single dish telescopes. With VLTI/GRAVITY, we can now spatially resolve not just the hot dust continuum on milliarcsecond scales through imaging but also the broad-line region on microarcsecond scales through spectro-astrometry. In this talk, I will review the latest results from our observations of local AGN with GRAVITY where we have mapped the kinematics of the BLR in seven nearby AGN, measured sizes of the hot dust for sixteen AGN, and reconstructed images for two AGN. BLR kinematics have allowed us to independently measure the BLR size and supermassive black hole mass where we begin to find a departure from the radius-luminosity relation at high luminosity. I will give an overview of the GRAVITY+ upgrades that will allow for direct black hole mass measurements out to high redshift and therefore a precise tracing of supermassive black hole-galaxy coevolution through cosmic time.  With the addition of wide-angle off-axis fringe tracking during the first phase of GRAVITY+, we have already pushed observations out to cosmic noon. I will show initial results from this program, including the first dynamical black hole mass measurement at high redshift which reveals an undermassive black hole that is accreting at super-Eddington rates.

16/04/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Martin Bureau (Oxford University)
18/04/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Early formation of galaxy discs
Filippo Fraternali (Kapteyn Astronomical Institute, University of Groningen)

Abstract

After decades of being mostly confined to the local Universe, the study of gas dynamics in galaxies, via a variety of emission-line gas tracers, has now become a key tool of investigation across cosmic time. The rotation of the gas allows us to trace the distribution of matter, quantify the mass and shape of the dark matter halos and study galaxy scaling relations. At the same time, gas turbulence reveals the effects of stellar feedback and disc instabilities and provides clues on the formation of the stellar thin/thick discs. I will present results on high-z rotation curves and velocity dispersions obtained through 3D reconstruction techniques of the emission-line datacubes. I will focus on ALMA observations of galaxies at z~4-5 observed in [CII] emission lines, extending to intermediate redshifts (z=1-4) using mostly CO lines. These data reveal fast rotation and relatively-low gas velocity dispersions leading to typical V/sigma values of order 10, similar to those of nearby spiral galaxies. Often, the fast rotations show the presence of mass concentrations that suggest a quick formation of stellar bulges, while the low velocity dispersions indicate that the gas turbulence is mostly fed by supernova feedback. I will discuss how the widespread presence of such “cold” discs at z~4-5 and their properties are changing our understanding of galaxy formation at early times.

19/04/24 (Friday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
ESO Talk
Talk — (topic to be announced)
Bill Dent (ALMA Observatory)
23/04/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Paolo Ventura (INAF - Osservatorio Astronomico di Roma)
25/04/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — Massive Black Holes: Insights from Cosmological Simulations
Tiziana Di Matteo (Carnegie Mellon University)

Abstract

The enigmatic journey of massive black holes, from the formation of a seed population in the early universe to their subsequent growth and mergers represents a vastly multi-scale phenomenon deeply intertwined with the process of galaxy formation. In this talk, I discuss the insights gleaned from cutting-edge cosmological simulations. These simulations not only provide some clues into the elusive population of Intermediate Mass Black Holes (IMBHs) but also shed light on some of the largest black holes in our Universe.

May 2024

02/05/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — DESI Progress and Results
Shaun Cole (Durham University)

Abstract

The main DESI redshift surveys have now collected 3 years of data and analysis of the Year-1 data set is almost complete. While concentrating  on the analysis of the Bright Galaxy Survey (BGS) in which I'm most directly involved  I plan to review the main cosmological results from other components of DESI. The BGS is a magnitude-limited (r<19.5) galaxy redshift survey and so rather like the SDSS main survey but about two magnitudes deeper. As such it is not only a useful cosmological probe but also a powerful probe of the local galaxy population and so a constraint on galaxy formation and the galaxy dark matter connection. I will present an analysis of how galaxy clustering depends on galaxyproperties and the galaxy luminosity function depends on environment.

07/05/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Kei Ito (University of Tokyo & ESO Visitor)
14/05/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Advancing precise line-driven wind mass-loss rate estimates in massive stars
Jiří Krtička (Masaryk University)

Abstract

On their way from the main sequence to the final supernova explosion, massive stars lose a substantial fraction of their mass through line-driven winds. Recent decades have witnessed significant advancements in both observational and theoretical studies of these winds that sail on starlight. The advancements in our understanding of radiative driving lead to progressively more accurate estimates of mass-loss rates from massive stars. In this talk, we will outline the key ingredients necessary for reliable predictions of mass-loss rates from numerical simulations, and demonstrate how state-of-the-art theoretical mass-loss rate estimates compare with observational results.

15/05/24 (Wednesday)
12:30, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
ESO Talk
Talk — Creativity in Science
Jian Wang (Leiden Institute of Advanced Computer Science)

Abstract

It is creativity/novelty that drives scientific breakthroughs and societal progress, but the journey from a novel scientific idea to a practical solution can be long and winding. Debates also persist regarding whether and how science contributes to practical solutions. In his talk, Jian will explore the complex relationship between novelty and impact in science and technological innovation. Furthermore, he will examine concerns that the current science funding system is increasingly risk-averse and favours short-term, safe projects over long-term, risky and novel projects. He will also present empirical evidence about whether major funding agencies are biased against novelty in their project selection process, and whether receiving funding enables grantees to engage more in novel research. Finally, he will discuss strategies that scientists can use to boost creativity, such as how to structure the professor-PhD student relationship, collaboration teams, and broader collaboration networks.

 

You can find the abstract and a short bio by the speaker at:

https://indico.euro-fusion.org/event/2559/page/18-highlight-topic-creativity-in-science

 

16/05/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — New constraints on structure growth from the abundance of massive halos
Sebastian Bocquet (LMU)
21/05/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — Gusts in the Headwind: uncertainties in direct dark matter detection
Grace Lawrence (UCL)

Abstract

High resolution, hydrodynamic galaxy simulations can be used to investigate the inherent variation of dark matter around the Solar Circle of a Milky Way-type galaxy. These simulations self consistently include both the baryonic back-reaction as well as assembly history of substructures, all of which may have lasting impacts on the dark matter’s spatial and velocity distributions, creating `gusts’ of dark matter wind around the Solar Circle, potentially complicating interpretations of direct detection experiments on Earth. Direct detection is a key experimental goal to advance the microscopic understanding of the dark matter that fills the Universe. We investigate how dark matter substructure, simulated in halos analogous to our own Milky Way, impacts the shape, summary statistics, and interpretation of results from terrestrial dark matter direct detectors.

Implementing a new numerical integration technique, our work generates bespoke predictions for terrestrial underground detection, finding large uncertainties arising in the expected signals of direct detection experiments. Having developed a realistic end-to-end pipeline for studying these effects, we discuss the implications of these astrophysical variations in the dark matter distribution of the solar neighbourhood on current and future particle physics searches for dark matter.

23/05/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — The colourful past and dark side of galaxies unveiled through population-dynamics of their stars
Glenn van de Ven (University of Vienna)
28/05/24 (Tuesday)
12:00, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Johanna Hartke (University of Turku)

June 2024

04/06/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Rahul Ramesh (University of Heidelberg)
06/06/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Raffaella Margutti (University of California, Berkeley)
13/06/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Barbara Ercolano (USM, Ludwig Maximilian University Munich)
18/06/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Armando Arellano Ferro (Instituto de Astronomía, Universidad Nacional Autónoma de México)
20/06/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Claude-Andre Faucher-Giguere (Northwestern University)
25/06/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Violette Impellizzeri (Leiden University)
27/06/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Myriam Benisty (IPAG/OCA)

July 2024

09/07/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Lorenzo Pino (INAF, Arcetri)
16/07/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Bo Reipurth (University of Hawaii)
18/07/24 (Thursday)
15:15, Auditorium Eridanus (ESO HQE, Garching) | ESO Garching
Munich Joint Astronomy Colloquium
Talk — (topic to be announced)
Ralph Pudritz (McMaster University)
23/07/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Alvaro Ribas (Cambridge)
30/07/24 (Tuesday)
12:00, Auditorium Telescopium (ESO HQE, Garching) | ESO Garching
Lunch Talk
Talk — (topic to be announced)
Eric Rohr (MPIA, Heidelberg)