Spectra of elliptic invariant differential operators on locally symmetric spaces

Abstract

For a locally symmetric space $\Gamma\backslash G /K$ we study the spectrum of the invariant differential operators of $G/K$ on $L^2(\Gamma\backslash G/K)$. This gives a purely analytical proof of the recent theorem of arXiv:2402.02530 that the quasiregular representation $L^2(\Gamma \backslash G)$ is tempered if the limit cone $\mathcal{L}_\Gamma$ of $\Gamma$ is contained in the interior of the Weyl chamber except if $G$ has real rank one or is locally isomorphic to $\mathfrak{sl}_3(\mathbb K)$, $\mathbb K=\mathbb{R},\mathbb{C},\mathbb H$, or $\mathfrak{e}_6^{-26}$.