Near optimal spectral gaps for hyperbolic surfaces

Abstract

We prove that if X is a finite area non-compact hyperbolic surface, then for any ϵ>0, with probability tending to one as n, a uniformly random degree n Riemannian cover of X has no eigenvalues of the Laplacian in [0,14ϵ) other than those of X, and with the same multiplicities.

As a result, using a compactification procedure due to Buser, Burger, and Dodziuk, we settle in the affirmative the question of whether there exists a sequence of closed hyperbolic surfaces with genera tending to infinity and first non-zero eigenvalue of the Laplacian tending to 14.

Authors

Will Hide

Durham University, Durham, United Kingdom

Michael Magee

Durham University, Durham, United Kingdom and Institute for Advanced Study, Princeton, NJ