Ruprecht-Karls-Universität Heidelberg

Vorträge, Seminare, Ereignisse

A list of all Physics & Astronomy talks and seminars taking place in Heidelberg can be found at HePhySTO.


Upcoming events


2021-06-22
16:00
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A new era of Interferometry with GRAVITY(+)
Dr. Frank Eisenhauer (MPI fuer Extraterrestrische Physik)
Heidelberg Joint Astronomical Colloquium ( Home pageHephysto link )
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https://zoom.us/j/97377192005?pwd=OUZPR1Z3ZGc5WDZPYW1SakEzV1pvQT09 The GRAVITY instrument has enabled major steps forward in infrared interferometry, by phase-referenced imaging at milli-arcsecond resolution, with a sensitivity increase by factor thousands, 30-100 micro-arcsecond astrometry, and few micro-arcsecond differential spectro-astrometry. We give an overview of the technology behind GRAVITY and highlight the game-changing results from the first three years of operation. Our presentation takes us from nearby exoplanets all the way to distant quasars, with special focus on the Galactic Center, the first precision tests of Einstein?s theory of General Relativity around massive black holes, and tests of the massive black hole paradigm on scales of 3-6 Schwarzschild radii. The GRAVITY+ project will soon boost optical interferometry to the next level, opening up the extragalactic sky for milli-arcsecond resolution interferometric imaging, and providing ever higher contrast for the observation of exoplanets. This will be made possible with wide-field fringe-tracking, new state-of-the-art adaptive optics, laser guide stars, and performance improvements of GRAVITY and the VLT(I) infrastructure. We discuss some of the discovery space opening up with GRAVITY+, for example the detailed view on AGN at cosmic dawn, the detection and characterization of exoplanets and their atmospheres, the spin of the Galactic Center black hole, and microlenses tracing the Milky Ways dark components. Dr. Eisenhauer is hosted by Dr. Diederik Kruijssen (kruijssen@uni-heidelberg.de)

2021-06-24
11:15
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Spatially mapping the metal-enriched absorbing CGM of a massive galaxy at z~4.5
Wuji Wang (ARI)
ARI Institute Colloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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High-redshift radio galaxies (HzRGs) are hosted by some of the most massive galaxies known at any redshift and are unique markers of concomitant powerful active galactic nuclei (AGN) activity and extreme starbursts. Their energetic radio jets, high star formation rates and black hole accretion rates place them amongst the most active sources at and near Cosmic Noon. Their extended gaseous environments of HzRGs are disturbed by outflows and inflows and show signs of significant jet-gas interactions making them unique objects in which quasar-mode feedback, radio-mode feedback and the host galaxies can be studied simultaneously. I will present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the 70 kpc x 30 kpc Lyman-alpha halo around a massive (10^11.8 M_sun) z = 4.5 radio galaxy. I will present our detailed spatially resolved spectral analysis of the complex Lyman-alpha profile in which we identify and measure the signatures (kinematics and column densities) of eight neutral gas absorbing systems at -3500 < v < 0 km/s. The strongest absorber at v ~0 km/s has a high covering fraction being detected across the extent of the Lyman-alpha halo, a significant column density gradient along the south to north direction and a velocity gradient along the radio jet axis. The absorber is also observed in in CIV and NV absorption, and very likely represents an outflowing metal-enriched shell driven by a previous AGN or star formation episode within the galaxy and is now caught up by the radio jet leading to jet-gas interactions. These observations provide evidence that feedback from AGN in some of the most massive galaxies the early Universe may take an important part in re-distributing material and metals in their environments. This work is part of larger sample of similarly massive, high-z radio galaxies and I will present the future plans for this unique sample of massive high-z galaxies hosting powerful AGN. JWST will be transformative for these galaxies as it will allow a detailed investigation on how radio- and quasar-mode feedback work together in the early Universe.

2021-06-25
15:00
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The Many Diverse Manifestations of Supermassive Black-Hole Feedback
Annalisa Pillepich (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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Feedback from super massive black holes (SMBHs) is commonly invoked in state-of-the-art large-scale cosmological galaxy simulations to halt star formation in massive galaxies. In fact, no other mechanism so far has been shown to be capable of returning entire populations of simulated massive quenched galaxies that are consistent with the observed galaxy red sequence and quenched fractions. In this talk, I will show how the IllustrisTNG cosmological simulations of galaxies allow us to gain insights and testable predictions on the manifestations of these energetic phenomena. With IllustrisTNG, with one unique set of physical ingredients, we simultaneously resolve and model the inner structural details of thousands of galaxies across five orders of magnitude in stellar mass, across environments, and together with the evolution and dynamics of the inter-stellar, circum-galactic and inter-galactic media. We are putting together ever more quantitative and plausible evidences as to the role that feedback from SMBH can have, not only in shaping galaxy structural properties and galaxy populations across 90 per cent of the Universe's history, but also in regulating the thermodynamical, ionization, and metal enrichment properties of the cosmic gas across halo scales and beyond. In particular, I will show how the IllustrisTNG model predicts that the gaseous atmospheres within and around galaxies are X-ray *brighter* for star-forming than for quiescent galaxies at the transitional mass scale of ~10^10-11 solar masses. I will discuss how novel results on the observed quenched fractions from SDSS support the ejective character of SMBH feedback from the central galaxies in groups and clusters at low redshift. And finally I will show that the TNG50 simulation naturally returns X-ray emitting bubbles that resemble the eROSITA and Fermi bubbles observed at the center of our Galaxy.

2021-07-01
11:15
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Constraining the Cosmic Baryon Cycle
Fabian Walter (Max Planck Institut für Astronomie, Heidelberg)
ARI Institute Colloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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New observations with ALMA have provided a census of the density of molecular gas in the cosmic volume defined by the Hubble Ultra-Deep Field. This molecular gas density shows an order of magnitude decrease as a function of redshift from z~2 to z=0. It follows, to first order, the dependence of the cosmic star formation rate density. This is remarkably different from the atomic gas phase that shows a rather flat redshift dependence. At low redshift, observations of the interstellar medium of nearby galaxies (in particular the HERACLES survey of molecular gas and the THINGS survey of atomic hydrogen) have demonstrated that the atomic gas is significantly more extended than the molecular gas (the latter being tightly correlated with star formation activity). A similar picture is also emerging in observations of high-redshift galaxies. Assuming a simple galaxy model based on these findings, and using other measurements from the literature, the ALMA Hubble Ultra-Deep Field data are used to put observational constraints on the gas (net) accretion flows in galaxies. These gas flows are needed to explain the build-up of the stellar mass in galaxies, and are further compared to cosmological galaxy formation simulations.

2021-07-02
15:00
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TBD
Til Birnstiel (LMU)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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TBD

2021-07-06
16:00
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Mapping the Ionized ISM in Nearby Galaxies
Dr. Kathryn Kreckel (ZAH, University of Heidelberg)
Heidelberg Joint Astronomical Colloquium ( Home pageHephysto link )
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2021-07-08
11:15
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Galaxies in voids: observational perspective
Evgeniya Egorova (Lomonosov Moscow State University, Sternberg Astronomical Institute)
ARI Institute Colloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Voids are low density regions in the Large Scale structure of the Universe. Due to the specific conditions, they are very well suited for the study of some fundamental questions: the search for predicted delayed galaxies, the study of galaxy evolution and star formation in extreme isolation, search for and study episodes of gas accretion onto galaxies, from companions or from gaseous filaments. According to the previous studies, voids contain the sizable fraction of gas-rich extremely metal-poor dwarf galaxies with metallicities of Z = (1/50-1/20) Z_solar. Their overall properties suggest their probable early stage of evolution. Therefore, they can be good real counterparts for predicted in recent simulations the Very Young Galaxies. Voids are considered as regions where the cold pristine gas accretion from large-scale filaments can still proceed. This may increase probability to find such unusual objects in the early stages of evolution. In order to get the most complete picture, it is worth studying void galaxies with various methods and approaches. In our analysis we use the optical spectral and photometrical data, ionized gas kinematics, as well as mapping of HI in the 21 cm line. I will present our study of processes affecting the evolution of void galaxies and the project on search for candidates to Very Young Galaxies. At the moment this project results in discovery of 10 new gas-rich XMP dwarfs with Z < 1/30 Z_solar.

2021-07-09
15:00
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TBD
Almudena Arcones (Uni. Darmstadt)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-07-13
16:00
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The Genesis of the First Elements
Dr. Ryan Cooke (University of Durham)
Heidelberg Joint Astronomical Colloquium ( Home pageHephysto link )
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2021-07-15
11:15
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Decoding the light of stars: Stellar Atmospheres and the crucial role of hot, massive stars
Andreas Sander (Armagh Observatory + ARI)
ARI Institute Colloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Almost everything we know about the Universe beyond our Earth stems from the light of stars. To decode the information that is imprinted in this light, we need to understand its origin in the outermost layers of the stars, the so-called "stellar atmosphere". Only a realistic physical model of these transition layers allows us to translate our observations into a proper understanding of stars. Consequently, stellar atmosphere models are a fundamental tool of modern astrophysics. In the massive star regime, Wolf-Rayet stars are a rare but important class of stars. A large fraction of Wolf-Rayet stars contains no or only a small amount of hydrogen, thereby providing a crucial benchmark for the late evolution of massive stars before collapsing into massive black holes. With mass-loss rates that are about ten times higher than those of O supergiants, just a few Wolf-Rayet stars are enough to easily outweigh the feedback of a whole population of OB stars. To properly understand and quantify the impact of Wolf-Rayet and other massive stars, their spectra need to be analyzed with the help of stellar atmosphere models. Located at the conjunction of theory and observation, my new Emmy Noether group at the ARI will investigate the parameters and impact of hot and massive stars with various approaches revolving around the use of current and next-generation stellar atmospheres. The seminar talk will provide an overview of the techniques and challenges of modern atmosphere models as well as outline the underlying concept for including a consistent hydrodynamic treatment. Focusing on the yet poorly understood winds of Wolf-Rayet stars, I will show recent results from a groundbreaking study of massive He-star atmosphere models, yielding the very first mass-loss recipe derived from first principles in this regime. With major consequences on e.g. maximum black hole masses or He II ionising fluxes, I will outline the importance of making progress in the field of stellar atmospheres and give a brief outlook on some of the core questions the new research group will address.

2021-07-20
16:00
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LHAASO Science Highlights
Prof. Zhen Cao (Institute for High Energy Physics, Beijing, China)
Heidelberg Joint Astronomical Colloquium ( Home pageHephysto link )
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2021-07-22
11:15
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MALT: Milky Way Archaeology using RR Lyrae and Type-II Cepheids
Hitesh Lala (ARI)
ARI Institute Colloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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RR Lyraes and Type-II Cepheids are old, low-mass variable stars and are invaluable distance indicators. We have created a comprehensive catalog of ~250,000 RR Lyraes and ~4000 Type-II & Anomalous Cepheids containing 7-D information (positions, proper motions, distances, radial velocities, metallicities). In the process, we have homogeneously combined 10 photometric and 6 spectroscopic surveys. Gaia EDR3 proper motions (and parallaxes) are available for ~95% of the sample. Using EDR3 parallaxes, along with the LMC population, we have derived new period-luminosity(-metallicity) and period-Wesenheit(-Metallicity) relationships in the Gaia DR2 & EDR3 GBPRP, VI, griz, JHKs, and W12 bands for all the sub-types (RRab, RRc, BL Her, W Vir, pW Vir, RV Tau, ACep_F, ACep_1O). Simultaneously solving the P-L/W relationships, we have computed individual reddenings (~15% uncertainty) to our sample stars. For our RR Lyrae sample (both RRab and RRc sub-types), we have also obtained photometric metallicity estimates on a new homogeneous scale creating the largest sample of RR Lyrae iron-abundances. Putting it all together, we have computed precise distances (~5% uncertainty) for an unprecedented number of RR Lyraes and Type-II Cepheids resulting in the most complete catalog yet of these populations. Harnessing this catalog, we have discovered many new members of Galactic streams and over-densities. For a few well-studied substructures like Orphan, Pal 5, GD-1, Sagittarius, etc., the re-discovery of known members helps us present more precise distances and metallicities for them, while the new ones enable precise measurement of these parameters for the very first time for many of the less-studied substructures. Our catalog places the community in a good state to exploit the imminent arrival of numerous spectra from WEAVE, 4MOST, DESI, Gaia DR3/4 and ultimately facilitate not only the chemo-dynamically analysis but also the discovery of several other streams and over-densities. The homogeneity of our catalog can also be exploited to uniformly study the Milky Way halo at unrivaled depths.

2021-07-23
15:00
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TBD
Steffi Walch-Gassner (Uni Cologne)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-07-30
15:00
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tbd
Stephan Stock (LSW)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)

2021-07-30
15:00
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Picture a Scientist
Movie Screening (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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The movie "Picture a Scientist" will be shown.

2021-08-06
15:00
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tbd
Stephan Stock (LSW)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)

2021-09-24
15:00
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TBD
Saskia Hekker (HITS)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)

2021-11-26
15:00
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Prize winners
Patzer colloquium
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-11-26
15:00
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Prize winners
Patzer colloquium
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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