Topological properties of Ad-semisimple conjugacy classes in Lie groups

Abstract

We prove that Ad-semisimple conjugacy classes in a connected Lie group $G$ are closed embedded submanifolds of $G$. We also prove that if $\alpha:H\to G$ is a homomorphism of connected Lie groups such that the kernel of $\alpha$ is discrete in $H$, then for an Ad-semisimple conjugacy class $C$ in $G$, every connected component of $\alpha^{-1}(C)$ is a conjugacy class in $H$. Corresponding results for adjoint orbits in real Lie algebras are also proved.