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Astro Seminar

Stellar black hole formation and dynamics across cosmic time

Speaker: Michela Mapelli (Padova)
Date: Thursday 25 June 2020
Time: 15:00
Venue: Zoom

The detection of gravitational waves opens new perspectives on the study of compact objects and challenges the astrophysical modelling of black hole formation. In this talk, I will discuss the main astrophysical formation channels of binary black holes in light of LIGO-Virgo data. On the one hand, models of stellar evolution and pair instability supernovae suggest a gap in the mass spectrum of black holes between ~60 and ~120 Msun. The boundaries of this gap depend on stellar rotation and on the efficiency of envelope removal. On the other hand, extreme dynamical processes in dense star clusters can fill the mass gap, via multiple stellar collisions and dynamical exchanges. Moreover, stellar dynamics enhances the formation of black hole -- neutron star systems with extreme (<1:10) mass ratios. Based on a data-driven model, I will discuss the merger history of dynamical versus isolated binary compact objects across cosmic time, and its dependence on the cosmic star formation rate and on the stellar metallicity.