Here is a tentative schedule for some of the remaining Miami 2020 conference talks.
LIGO session 1
Thursday, 10 December, 10:00 AM EST (= UTC -05:00) Three talks, approximately 30 minutes each, accessible via the following Zoom URL: https://miami.zoom.us/j/97718734520?pwd=WWFvV1FJRU5HMU9Ra2E3Z0wra0FpUT09
Sergey Klimenko
Professor, Department of Physics
University of Florida
GW190521: an “Impossible” Binary Black Hole.
Abstract: With the first direct observation of gravitational waves (GW) on September 14, 2015, the advanced GW detectors opened new possibilities to explore our Universe. This first GW signal was not from a much-anticipated binary neutron stars (BNS), but from a quite unexpected merger of binary black holes (BBH). Now, five years later, the GW detectors have recorded two BNS and more then 50 BBH signals, including GW190521 - a missing link between stellar mass black holes and supermassive black holes. This is another unexpected BBH event, which is not possible to be formed by the evolution of isolated massive stars. I will talk about LIGO and observation of the most massive BBH event informing our understanding of the evolution of the most massive stars and the grows of massive black holes.
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Imre Bartos
Assistant Professor of Physics, Alfred P. Sloan Foundation Research Fellow
University of Florida
Black hole assembly lines in AGN disks
ABSTRACT: Since their first discovery in 2015, gravitational-wave observations yielded several "surprises." The LIGO and Virgo observatories detected more and heavier black holes than anticipated; the first object in the lower mass gap was found; and a few weeks ago, LIGO announced the discovery of a particularly heavy black hole within the binary GW190521 that is difficult to explain with our current models of stellar core collapse. The surprises point to the possibility that some of LIGO/Virgo's black hole mergers occurred in the dense accretion disks of active galactic nuclei (AGNs). AGNs act like a black hole assembly line, resulting in multiple consecutive mergers that create heavier and faster spinning black holes. I will discuss what we currently know about AGN-assisted mergers and which of LIGO/Virgo's events are suspects. Another unique possibility in AGNs is accretion onto the black holes that can produce an electromagnetic counterpart to the mergers. I will briefly introduce this possibility.
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Michela Mapelli,
Professor, Physics and Astronomy Department "G. Galilei"
University of Padova
GW190521: Crafting an impossible black hole
GW190521 is the most massive gravitational wave event to date, and its primary mass has astrophysicists scratching their heads: it lies in the middle of the upper mass gap, expected from the theory of pair instability. Uncertainties on massive star evolution (e.g., rotation, envelope undershooting, convection, nuclear rates and envelope collapse) still leave some ground for a deep revision of the mass gap. Alternatively, multiple mergers and runaway collisions of massive stars in metal-poor star clusters might facilitate the formation of massive (~60-400 Msun) black holes with possibly large spins. In the absence of a natal kick, these oversized black holes remain in the parent cluster and can easily pair with other compact objects.
