Zariski dense non-tempered subgroups in higher rank of nearly optimal growth

Fuente: arXiv
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Main Authors: Fraczyk, Mikolaj, Oh, Hee
Format: Preprint
Published: 2024
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author Fraczyk, Mikolaj
Oh, Hee
author_facet Fraczyk, Mikolaj
Oh, Hee
contents We construct the first example of a Zariski-dense, discrete, non-lattice subgroup $Γ_0$ of a higher rank simple Lie group $G$, which is non-tempered in the sense that the quasi-regular representation $L^2(Γ_0\backslash G)$ is non-tempered. More precisely, let $n\ge 3$ and let $Γ$ be the fundamental group of a closed hyperbolic $n$-manifold that contains a properly embedded totally geodesic hyperplane. We show that there exists a non-empty open subset $\mathcal O$ of $\operatorname{Hom}(Γ, \operatorname{SO}(n,2))$ such that for any $σ\in \mathcal O$, the subgroup $σ(Γ)$ is a Zariski-dense and non-tempered Anosov subgroup of $\operatorname{SO}(n,2)$. In addition, the growth indicator of $σ(Γ)$ is nearly optimal: it almost realizes the supremum of growth indicators among all non-lattice discrete subgroups, a bound imposed by property $(T)$ of $\operatorname{SO}(n,2)$.
format Preprint
id arxiv_https___arxiv_org_abs_2410_19551
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Zariski dense non-tempered subgroups in higher rank of nearly optimal growth
Fraczyk, Mikolaj
Oh, Hee
Group Theory
Dynamical Systems
Geometric Topology
Representation Theory
Spectral Theory
We construct the first example of a Zariski-dense, discrete, non-lattice subgroup $Γ_0$ of a higher rank simple Lie group $G$, which is non-tempered in the sense that the quasi-regular representation $L^2(Γ_0\backslash G)$ is non-tempered. More precisely, let $n\ge 3$ and let $Γ$ be the fundamental group of a closed hyperbolic $n$-manifold that contains a properly embedded totally geodesic hyperplane. We show that there exists a non-empty open subset $\mathcal O$ of $\operatorname{Hom}(Γ, \operatorname{SO}(n,2))$ such that for any $σ\in \mathcal O$, the subgroup $σ(Γ)$ is a Zariski-dense and non-tempered Anosov subgroup of $\operatorname{SO}(n,2)$. In addition, the growth indicator of $σ(Γ)$ is nearly optimal: it almost realizes the supremum of growth indicators among all non-lattice discrete subgroups, a bound imposed by property $(T)$ of $\operatorname{SO}(n,2)$.
title Zariski dense non-tempered subgroups in higher rank of nearly optimal growth
topic Group Theory
Dynamical Systems
Geometric Topology
Representation Theory
Spectral Theory
url https://arxiv.org/abs/2410.19551