Abstract: In this talk, I shall describe how to define mass in general relativity and describe the motivation behind the construction.
Andreas Burkert Ludwig-Maximilians Universität München
Abstract: Star formation, despite its importance, is not well understood up to now. Galaxies, like the Milky Way contain large quantities of cold, dense molecular gas that should collapse gravitationally and burst into stars on a timescale of order a few million years. As a result, galaxies should be burned out by now which is in contrast to observations. The Milky Way is still actively forming stars, allowing late generations of stars like the Sun to form at a time where the Galaxy was substantially enriched with heavy elements and dust which provided the raw material for planets and life.
I will discuss a new idea of self-regulated star formation that builds on the assumption that it the continuous flow of gas through the various gas phases that regulates the thermodynamics of the interstellar medium and process of star formation. For example, the star formation rate of a molecular cloud is not determined by it’s total gas mass but by the rate with which the cloud accumulates more gas. I will apply this bathtub model to Orion cloud and demonstrate that this best studied prototype star forming region must actually have formed under very extreme, unlikely conditions, that are unmatched elsewhere.
Abstract: I will explain a new proof of the non-linear stability of the Minkowski spacetime as a solution of the Einstein vacuum equation. The proof relies on an iteration scheme at each step of which one solves a linear wave-type equation globally. The analysis takes place on a suitable compactification of R^4 to a manifold with corners whose boundary hypersurfaces correspond to spacelike, null, and timelike infinity; I will describe how the asymptotic...
Abstract: The much-anticipated joint detection of gravitational waves and electromagnetic radiation was achieved for the first time on August 17, 2017, for the binary neutron star merger GW170817. This event was detected by Advanced LIGO/Virgo, gamma-ray satellites, and dozens of telescopes on the ground and in space spanning from radio to X-rays. In this talk I will describe the exciting discovery of the optical counterpart, which in turn led to several detailed studies across the electromagnetic spectrum. The results of the observations carried out by our team include the first detailed study of a "kilonova", an optical/infrared counterpart powered by the radioactive decay of r-process nuclei synthesized in the merger, as well as the detection of an off-axis jet powering radio and X-ray emission. These results provide the first direct evidence that neutron star mergers are the dominant site for the r-process and are the progenitors of short GRBs. I will also describe how studies of the host galaxy shed light on the merger timescale, and describe initial constraints on the Hubble Constant from the combined GW and EM detection. ... Read more about BHI Colloquium, December 12 | "Rattle and Shine: Joint Detection of Gravitational Waves and Light from the Binary Neutron Star Merger GW170817," Edo Berger