Evolution of the Black Hole Mass Function in Star Clusters from Multiple Mergers

Pierre Christian, Philip Mocz, Abraham Loeb

Published 2018-03-19Version 1

We investigate the effects of black hole mergers in star clusters on the black hole mass function. In particular, supernova theory suggests that there is a dearth of black holes between 50-130 Solar masses, while parameter fitting of X-ray binaries suggests the existence of a gap in the mass function under 5 Solar masses. We show, through evolving a coagulation equation, that black hole mergers can appreciably fill the upper mass gap, and that the lower mass gap generates potentially observable features at larger mass scales. We also explore the importance of ejections in such systems.