Who are the parents of LIGO’s black holes? Stars, most likely. Things like those we see in the sky at night will eventually surrender to gravity and collapse. Some of them will form black holes. Some of them will form binary black holes. Some of them will merge. Some of them will be observed by LIGO. That’s the vanilla story at least, but it might not apply to all of the black holes that LIGO sees. For some of those, stars might be the grandparents or the great grandparents. And the parents are … just other black holes! This is today’s paper lead by Vishal Baibhav. Instead of just measuring the properties of the black holes that LIGO observes, we show we can also say something about the features of the black hole parents. Read on to explore the black-hole family tree.

Vishal Baibhav, Emanuele Berti, Davide Gerosa, Matthew Mould, Kaze W. K. Wong.
Physical Review D 104 (2021) 084002.
arXiv:2105.12140 [gr-qc].