Ruprecht-Karls-Universität Heidelberg

Talks, Seminars, Events

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


Upcoming events


2020-10-30
15:00
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Anders Jidesjö & Svein Sjøberg (TBA)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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Blocked for talk related to ROSE/IAU OAE.

2020-11-05
11:15
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A Light in the Dark - Massive Star Birth Through Cosmic Time
Jonathan Tan (Chalmers Uni & University of Virginia)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Massive stars have played a dominant role in shaping our universe since its earliest times, but there is still no consensus on the mechanism by which they form. I review the physics that is important for massive star formation and the connection this process may have with star cluster formation. I then focus on a particular theoretical model, Turbulent Core Accretion, which assumes the initial conditions are massive, turbulent, magnetized cores of gas and dust that are reasonably close to virial equilibrium. Our group has been exploring this scenario via analytic models and numerical simulations of the physics and chemistry of the interstellar medium, ranging from the earliest pre-stellar core phase to protostellar cores being impacted by strong self-feedback. Crucially, these models can now be tested in detail with ALMA, SOFIA and other facilities, and I present the latest results from multiple projects that are zooming in to massive star birth in the darkest shadows of giant molecular clouds. Extension of this work has the potential to also determine how the full stellar initial mass function is established across different Galactic environments. Finally, I discuss an application of massive star formation theory to the early universe: how massive were the first stars and could they have been the progenitors of supermassive black holes?

2020-11-06
15:00
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Maryam Modjaz (NYU)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2020-11-06
15:00
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Maryam Modjaz (NYU)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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2020-11-12
11:15
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CAPTURE OF INTERSTELLAR ASTEROIDS AND COMETS
Walter Dehnen (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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The recent by fly-bys of Oumuamua and Borisov suggest a large space density of such interstellar asteroids and comets. I investigate the possibility of capturing such objects into the Solar system via a fly-by of Jupiter or Saturn, presenting analytical arguments and estimates as well as results of various numerical simulations. The most likely captures occur for an incoming speed of around 0.6 km/s and populate orbits akin to those occupied by long-period comets. We estimate that the Solar system may contain around 10000 captured Oumuamua-like asteroids and 100 captured comets.

2020-11-13
15:00
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Maryam Modjaz (NYU)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2020-11-13
15:00
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ASPECS - The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (www.aspecs.info)
Fabian Walter (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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I will report on some of the results emerging from the ALMA large program ASPECS (aspecs.info). ASPECS obtained deep imaging in the 1mm and 3mm bands of the Hubble Ultra-Deep Field (H-UDF) through frequency scans. The observations provide a full census of dust and molecular gas in the H-UDF, down to masses that are typical of main-sequence galaxies at redshifts 1-4. The resulting data products enable a great range of studies, from the characterisation of individual galaxies, capitalizing on the unique multi-wavelength dataset of the H-UDF, to CO excitation studies to constrain the gas properties of the distant galaxies. A 3D stacking analysis using precise redshifts from major VLT/MUSE initiatives on the field helped in recovering additional emission of galaxy samples that are too faint to be detected individually. Stacking in both the continuum and line (capitalizing on 100s of spectroscopic redshifts from major VLT/MUSE initiatives on the H-UDF) pushed the detection limits further. The nature of the observations (full spectral scans) provides a census of dust and molecular gas in the cosmic volume defined by the H-UDF. The resulting cosmic molecular gas density as a function of redshift shows an order of magnitude decrease from z=2 to z=0. This is markably different from independent measurements of the atomic gas phase that shows a rather flat redshift dependence. These measurements can be used to put new constraints on the gas accretion process that is needed to explain the build-up of stellar mass in galaxies through cosmic history.

2020-11-19
11:15
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Studying quasar microlensing with robots
Robert Schmidt (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Gravitationally lensed quasars are mirages where a background quasar is observed several times due to the light deflection by a foreground galaxy. Microlensing along the individual light paths causes variability of the quasar images, which lets us draw conclusions on the microlensing objects and the quasar engine. I sum up the state of the art and describe our monitoring program which uses the LCOGT robotic telescopes.

2020-11-20
15:00
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Jonathan Henshaw (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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2020-11-26
11:15
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Fabian Schneider (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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2020-11-27
15:00
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Patzer Colloquium (MPIA/ZAH)
Königstuhl Kolloquium ( Home pageHephysto link )
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2020-12-03
11:15
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NGC6240: Triple supermassive black holes in simulation and observation. Kozai-Lidov Effect and the timescale of PN merging.
Peter Berczik (Main Astronomical Observatory, Kyiv)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Abstract
One of the possible ways of creating the supermassive black hole (SMBH) is hierarchical merging scenario. Central SMBHs at interacting and coalescing host-galaxies are observed as SMBH candidates at different separations from hundreds of pc to mpc. One of the strongest SMBHs candidates is ULIRG galaxy NGC6240 which was X-ray spatially and spectroscopically resolved by Chandra. Researching of central SMBHs merging in dense stellar environment allows to retrace their evolution from kpc to mpc scales. The main goal of our dynamical modeling was to reach the gravitational wave (GW) emission regime for the multiple BHs model. We present the direct N-body simulations with up to one million particles and relativistic post-Newtonian corrections for the SMBHs particles up to 3.5PN. From our models we found the upper limit of merging time for NGC6240 central SMBHs is less than ~50 Myr.

2020-12-04
15:00
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TBD
HH2020 speaker (CfA)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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2020-12-10
11:15
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Gaia Early Data Release 3
Stefan Jordan (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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On December 3, 2020, the first (early) part of Gaia’s third star catalogue will be published. Based on 34 months of Gaia observations it contains a significant increase in the number of entries compared to Gaia DR2: position measurements of more than 1.8 billion stars as well as proper motions, parallaxes, and broad-band photometry for about 1.4 billion stars. Additionally, both the precision and accuracy of the astrometric data has significantly improved, especially the determination of proper motions. Together with the release of the star catalogue, four papers are published, impressively demonstrating the scientific potential of the Gaia EDR3 catalogue.

2020-12-11
15:00
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Diederik Kruijssen (ARI)
Königstuhl Kolloquium ( Home pageHephysto link )
Via zoom link. Please contact organisers if you need the zoom information.,
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2020-12-17
11:15
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Science Forgeries, Fraud, Fake Science Across Scientific Disciplines and Their Consequences
Eva Grebel (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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The above was the subject of a Marsilius Project at Heidelberg University undertaken jointly by the art historian Prof. Henry Keazor and myself, triggered by my experiences in the DFG commission for investigations of scientific misconduct and his work on exposing art forgeries. I will present a summary of our findings on the different types of such misconduct across different disciplines, discuss the motivation of the perpetrators and ways of preventing misconduct, as well as talk about the consequences for science, scientific credibility, political and economic decisions, and public perception in general.

2020-12-18
15:00
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Laura Kreidberg (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
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2021-01-08
15:00
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Connecting the dots: Numerical models of AGN and their particle acceleration
F. Spanier (ITA)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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Active Galactic Nuclei are an interesting source not only for photons in a very wide energy range, but also for cosmic rays and neutrinos. The emission of these different messengers is most likely connected to each other. To understand the physics behind AGN, emission models have to be constructed. Nowadays observational data is available from radio frequencies to TeV energies and neutrino observatories like IceCUBE may provide ultra-high energy neutrino counts. Unfortunately long-term simultaneous multi-wavelength observations are still scarce. I will present results from time-dependent and spatially resolved AGN emission models that allow for a self-consistent treatment of emission and particle acceleration within AGN. These models may help to distinguish different emission processes using the timing of lightcurves in separate energy bands. But they may also provide answers to questions like "What is the shape of an AGN jet?" or "Is there really one neutrino per one high-energy photon?"

2021-01-14
11:15
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The power of asteroseismology: the internal structure of stars
Saskia Hekker (HITS and LSW)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Over the past decade the space missions CoRoT, Kepler and TESS have revolutionised the field of asteroseismology ? the study of the internal structures of stars through their global intrinsic oscillations. A particular steep increase in our knowledge has been possible in stars cooler than ~ 6700 K, which exhibit convection in their outer layers. Oscillations are excited in these turbulent layers that allow us to probe large parts of the stars. In this talk I will present recent results of asteroseismic inferences of the stellar structure of these cool stars.

2021-01-15
15:00
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Brauer Award talk
Sarah Leslie (Leiden)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-01-21
11:15
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Refining the picture of galaxy regulation with observations & theory
Benjamin Keller (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Stellar feedback connects the smallest, densest scales of the galaxy to the largest, most diffuse components of the galaxy halo. The detailed, fractal structure of the interstellar medium (ISM) and the evolution of stars sets the local coupling efficiency of energy from stellar winds, radiation and supernovae. This feedback can then drive outflows from most galaxies, removing mass and metals to the diffuse, hot circumgalactic medium. This low-density halo can act as a reservoir for material, slowly allowing it to re-accrete and fuel ongoing star formation. This in turn influences the formation of new molecular clouds within the ISM, connecting the process of star formation to all scales of the galaxy's gas content. In this talk, I will present recent results that have helped to clarify the details as to how the details of these processes can impact the overall life of galaxies, and how we can use new observational and statistical methods to constrain these details.

2021-01-22
15:00
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Trifon Trifonov (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-01-28
11:15
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The role of star formation environment for planet formation
Andrew Winter (ITA)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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The diverse architectures of discovered exoplanetary systems have provoked an equally diverse range of explanations of the processes governing their formation and evolution. However, the star formation environment is a factor that is frequently overlooked in studies that aim to synthesise the observed planet properties. I review the growing evidence suggesting that environmental feedback plays a significant role during and after planet formation. Two mechanisms that may be particularly influential are external photoevaporation due to irradiation of the protoplanetary disc by neighbouring OB stars, and subsequently star-star encounters that can generate instability in the mature planetary system. I discuss observational constraints and examples of these mechanisms caught in the act, and how they might alter a system from that which forms ?in isolation'. Finally, I contextualise the Solar System in terms of possible environmental sculpting.

2021-01-29
15:00
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Sarah Bosman (MPIA)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-02-04
11:15
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Microlensing events all over the sky - the promise of large-scale surveys
Markus Hundertmark (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Modern wide-field surveys will provide us with alert streams generating millions of alerts every night and by that providing a comprehensive picture of the variable sky. Traditionally, microlensing events have been found in the most crowded place in the Milky Way. Thanks to the footprint, microlensing events in the disk will play an increasingly important role. The opportunities opening up by these surveys will lead to more discoveries and the characterization of extrasolar planets (bound and unbound), black holes and insights into the binarity of stars and brown dwarfs. The most audacious surveys will certainly provide the best alert stream but some of the aforementioned science cases still require automated follow-up observations. The "fire-hose of alerts" demands cloud-based tools to trigger heterogeneous follow-up observations with a homogeneous software package - the TOM (Target and Observation Manager) Toolkit. We will show early results from the most recent observing programs running at Las Cumbres Observatory (LCO) global network using a TOM and how that can be applied to the surveys of the future.

2021-02-11
11:15
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Ready for the next gravitational million-body simulations: Evolution of single and binary stars in NBODY6++GPU and MOCCA
Albrecht Kamlah (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Direct N-body simulations are the only simulation method capable of properly resolving dense star clusters from the scales between close interacting stars in a binary all the way up to their interaction with distant halo stars. Nevertheless, they are frequently complemented with approximate Monte-Carlo methods, because these are much quicker computationally. Recently, there have been a number of code advances concerning the stellar evolution. This is crucial, as the evolution of individual stars has a huge effect on the overall dynamical evolution of a star cluster and thus amongst others the formation of gravitational wave emitting sources that may be detectable with LIGO and VIRGO. In this talk, I will highlight the state of stellar evolution routines in the direct N-body code NBODY6++GPU and the Henon-type Monte-Carlo code MOCCA by comparing the results of small star cluster simulations performed with both. The results of these are important groundwork to ensure that the upcoming million-body simulations of globular and nuclear star clusters are astrophysically up-to-date.

2021-02-12
15:00
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Dominika Wylezalek (ZAH/ARI)
Königstuhl Kolloquium ( Home pageHephysto link )
Max-Planck-Institut für Astronomie, Level 3 Lecture Hall (301)
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2021-02-18
11:15
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Breaching the barrier: dynamical formation of the first intermediate-mass black hole discovered by LIGO-Virgo
Manuel Arca Sedda (ARI)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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On September 2nd 2020, the LIGO-Virgo collaboration announced the detection of GW190521, a gravitational wave source associated with the merger of two black holes (BHs), 66 and 85 Mo masses, which left behind an intermediate-mass black hole (IMBH) with a mass of 142 Mo. This binary merger is peculiar because its primary mass falls in the so-called upper mass-gap, a region of stellar masses where modern stellar evolution predicts the absence of remnants, and the final remnant represents the first specimen of a "light" IMBH. In this seminar, I will describe a novel channel suitable to explain the properties of GW190521, namely a sequence of three mergers among stellar mass black holes. We discovered serendipitously such a process in a high-resolution N-body model of a dense star cluster. We combine these simulations with an analysis based on numerical relativity fitting formulae and on observed properties of globular, young, and nuclear clusters, to show that if GW190521 originated via such a mechanism its observation gives us insights on the distribution of stellar BH natal spins and on the environment that harboured such a system, most likely a dense and young star cluster.

2021-02-25
11:15
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Formation and evolution of supermassive black holes.
Melanie Habouzit (MPIA and LSW)
ARI Institute Kolloquium ( Hephysto link )
ARI, Moenchhofstrasse 12-14, Seminarraum 1, 1.OG
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Supermassive black holes of million solar mass and above are commonly hosted by massive galaxies, but are also present in local dwarf galaxies. Black holes are a fundamental component of galaxies and galaxy evolution, but their origin is still far from being understood. Large-scale cosmological simulations are crucial to understand BH growth and their interplay with their host galaxies. We recently compared the black hole population of six of these large-scale cosmological simulations (Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA) and I will review how the simulation sub-grid models affect the build-up of the BH population and their correlations with galaxies properties. The next two decades will be dedicated to the exploration of the high-redshift Universe with upcoming space missions such as LynX, Athena, JWST, WFIRST, and LISA. I will present how we can use cosmological simulations to prepare these missions and maximize their scientific return.

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