Growth of Seed Black Holes in Galactic Nuclei

TL;DR

This paper uses high-accuracy N-body simulations to study the evolution of dense star clusters, revealing the growth of intermediate mass black holes and frequent binary black hole mergers within star clusters, relevant to gravitational wave observations.

Contribution

It introduces detailed simulations incorporating stellar evolution and relativistic effects, demonstrating black hole growth and mergers in star clusters, aligning with recent gravitational wave detections.

Findings

Growth of intermediate mass black holes in star clusters

Frequent binary black hole mergers in the pair creation supernova gap

Simulation results consistent with LIGO-Virgo-KAGRA observations

Abstract

The evolution of dense star clusters is followed by direct high-accuracy N-body simulation. The problem is to first order a gravitational N-body problem, but stars evolve due to astrophysics and the more massive ones form black holes or neutron stars as compact remnants at the end of their life. After including updates of stellar evolution of massive stars and for the relativistic treatment of black hole binaries we find the growth of intermediate mass black holes and we show that in star clusters binary black hole mergers in the so-called pair creation supernova (PSN) gap occur easily. Such black hole mergers have been recently observed by the LIGO-Virgo-KAGRA (LVK) collaboration, a network of ground based gravitational wave detectors.