Events, Seminars, Talks

Abstract
Giant low surface brightness galaxies (gLSBGs) have the largest discs in the Universe with the radii up to 130 kpc. The formation of such enormous discs is a stress-test for the hierarchical galaxy formation paradigm and without clarifying it we cannot paint a coherent picture of galaxy evolution. In the talk I will give the answers to the following questions. How rare are gLSBGs? What are the formation scenarios of gLSBGs? And how does it all correspond to the results of modern cosmological simulations? These answers are based on both in-depth study of 8 gLSBGs, including the results of our deep spectroscopic and photometric observations, HI data collected in the framework of our observing programs and complemented by archival datasets. Finally, we used deep optical images from HSC Subaru Strategic Program and publicly available redshift catalogs, estimated the volume density of gLSBGs in the local Universe and compared it to state-of- the-art numerical simulations.

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In this talk I will describe how mapping the dynamics of gas clouds in the centre of galaxies can help us to constrain a wide range of astrophysical problems. From the enigmatic relation between galaxies and their supermassive black holes, to the suppression of star-formation in dying galaxies, the dynamics of cold gas provides an ideal probe that can help us make progress. I will show how ~ten parsec resolution ALMA observations can be used to estimate the masses of supermassive black holes in galaxies across the Hubble sequence, both dynamically, and via the newly discovered ‘fundamental plane of black hole accretion in the millimetre”. I will show that the deep potential wells of massive galaxies change the small-scale structure of the ISM, suppressing star formation, and helping to keep bulge-dominated objects quenched. Finally I will show first results from the KILOGAS project, a new ALMA legacy survey for the resolved extragalactic ISM, that will map molecular gas and star formation across the Hubble sequence in nearly 500 nearby galaxies. To arrange a visit with the speaker during the visit, please contact their host: Dominika Wylezalek

Abstract
DRAGON star cluster simulations have provided the first fully realistic long-term simulations of globular star clusters, have reproduced LIGO/Virgo observed binary black hole mergers, and are now entering into the next phase to simulate more massive, young and nuclear star clusters. They are based on the direct N-body simulation code Nbody6++GPU. In the talk an introduction and overview to direct N-body simulation and DRAGON simulations is given. Two current new applications are then shown, first initially very dense star clusters which form quickly an intermediate mass black hole of order 50.000 solar masses, which could be a seed for massive black holes in the early universe. Second, a still ongoing project is discussed, in which an already pre-existing supermassive black hole in a nuclear star cluster is followed, how it tidally disrupts stars, and captures low-mass stars, white dwarfs, neutron stars and stellar mass black holes.

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By precisely measuring the motions of stars on the sky over time, the Gaia mission is conducting a comprehensive census of the Milky Way's binary stars. These data are transformative both for population modeling and for discovery of rare objects. I will describe our emerging view of the populations of black holes, neutron stars, and white dwarfs in au-scale binaries, focusing in particular on their mass, period, and eccentricity distributions. Compared to previous surveys, Gaia is revealing post-interaction binaries in wider orbits, whose properties are difficult to explain with standard binary evolution models. I will discuss how the Gaia catalogs can be leveraged for statistical inference, despite their complex selection function, and how they can discriminate between competing formation models.

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KoCo Signature Speaker (GC)