Effect of angular momentum distribution on gravitational loss-cone instability in stellar clusters around massive BH

TL;DR

This paper investigates how the distribution of angular momentum affects the stability of stellar clusters around massive black holes, revealing that non-monotonic distributions lead to instability in spherical clusters, while disk clusters can be unstable regardless.

Contribution

It demonstrates the critical role of angular momentum distribution shape in the gravitational loss-cone instability of stellar clusters near black holes.

Findings

Non-monotonic angular momentum distributions cause instability in spherical clusters.

Disk clusters can be unstable for both monotonic and non-monotonic distributions.

Stability depends on the angular momentum distribution shape.

Abstract

Small perturbations in spherical and thin disk stellar clusters surrounding massive a black hole are studied. Due to the black hole, stars with sufficiently low angular momentum escape from the system through the loss cone. We show that stability properties of spherical clusters crucially depend on whether the distribution of stars is monotonic or non-monotonic in angular momentum. It turns out that only non-monotonic distributions can be unstable. At the same time the instability in disk clusters is possible for both types of distributions.