Boosting the growth of intermediate-mass black holes: collisions with massive stars

TL;DR

This study uses relativistic simulations to analyze collisions between intermediate-mass black holes and massive stars, demonstrating rapid black hole growth and some ejected material in dense stellar environments.

Contribution

It provides the first detailed relativistic simulation results of black hole-star collisions, showing their role in black hole mass growth in stellar clusters.

Findings

Most stellar material is accreted onto the black hole rapidly.

A small fraction of mass is ejected and shock-heated.

Collisions significantly contribute to black hole growth in clusters.

Abstract

We perform fully relativistic simulations of the head-on collisions between intermediate-mass black holes and very massive stars. Such collisions are expected to occur in dense stellar clusters and may play an important role in growing the mass of the seed black hole. For the cases considered here, for which the masses of the black holes and stars are comparable, the vast majority of the stellar material is accreted onto the black hole within a stellar dynamical timescale, as expected from analytical estimates, and leads to a rapid growth of the black hole. A small amount of mass, which is shock-heated in the wake of the black hole, is ejected from the collision and will contribute to the interstellar material in the cluster.