Acylindrical Hyperbolicity of Subgroups

Abstract

Suppose $G$ is a finitely generated group and $H$ is a subgroup of $G$. Let ${\partial }_c^{\mathcal{FQ}}G$ denote the contracting boundary of $G$ with the topology of fellow travelling quasi-geodesics defined by Cashen-Mackay \cite{cashen2017}. In this article, we show that if the limit set $\Lambda (H)$ of $H$ in ${\partial }_c^{\mathcal{FQ}}G$ is compact and contains at least three points then the action of the subgroup $H$ on the space of distinct triples ${\Theta }_3(\Lambda (H))$ is properly discontinuous. By applying a result of B. Sun \cite{BinSun}, if the limit set $\Lambda (H)$ is compact and the action of $H$ on ${\partial }_c^{\mathcal{FQ}}G$ is non-elementary then $H$ becomes an acylindrically hyperbolic group

Minor errors corrected. Accepted in NYJM