Stable bound orbits around static Einstein-Gauss-Bonnet black holes

TL;DR

This paper investigates the existence of stable bound orbits around static Einstein-Gauss-Bonnet black holes in higher dimensions, revealing parameter ranges and conditions under which such orbits can exist, including in AdS backgrounds.

Contribution

It identifies the parameter space allowing stable bound orbits in higher-dimensional Einstein-Gauss-Bonnet black holes, including the lower bound of the coupling constant and the existence of multiple stable orbits in AdS cases.

Findings

Stable bound orbits exist in certain parameter ranges for 6-9 dimensions.

A lower bound on the Gauss-Bonnet coupling constant is necessary for stable orbits.

Multiple stable circular orbits can exist outside the horizon in AdS black holes.

Abstract

As is well-known, asymptotically flat, static and spherically symmetric black holes do not admit stable bound orbits of massive/massless particles outside the horizon in higher-dimensional Einstein gravity. However, for massive particles, this dramatically changes in higher curvature theories. We clarify the parameter range such that there exist stable bound orbits in $d$-dimensional Einstein-Gauss-Bonnet theories for $6\leq d\leq 9$. In particular, we show the existence of the lower bound of the Gauss-Bonnet coupling constant below which stable bound orbits cease to exist. Moreover, we also find that for AdS-black holes in the theories, there can exist two stable circular orbits outside the horizon.