Davide Gerosa

University of Birmingham

Escape speed of stellar clusters from multiple-generation black-hole mergers in the upper mass gap

Davide Gerosa, Emanuele Berti.
arXiv:1906.05295 [astro-ph.HE].

Funny things happen in supernova explosions. Funny and complicated. If the star is too massive, the explosion is unstable. The black hole it formed it not as massive as it could have been. In gravitational-wave astronomy, this means that we should not observe black holes heavier than about 50 solar masses. This does not apply, of course, if black holes are not formed from stars, but from other black holes (yes! more black holes!). If black holes somehow stick around, they could be recycled in other generations of mergers. We point out that this can work only if their astrophysical environment is dense enough. Can we measure the escape speed of black holes “nurseries” using gravitational-wave events that should not be there because of supernova instabilities?

Gravitational-wave detection rates for compact binaries formed in isolation: LIGO/Virgo O3 and beyond.

Vishal Baibhav, Emanuele Berti, Davide Gerosa, Michela Mapelli, Nicola Giacobbo, Yann Bouffanais, Ugo N. Di Carlo
arXiv:1906.04197 [gr-qc].

LIGO and Virgo are up and running like crazy. They started their third observing run (O3) and in just a few months doubled the catalogs of observing events. And there’s so much more coming! In this paper we try to work out “how much” using our astrophysical models. Figure 4 is kind of shocking: we’re talking about thousands of black holes in a few years, and millions of them in 20 years. Need to figure out what to do with them…