Spectral gap for Pollicott-Ruelle resonances on random coverings of Anosov surfaces
Julien Moy
TL;DR
The paper proves a near-optimal spectral gap for Pollicott–Ruelle resonances of the geodesic flow on random degree‑n coverings of a closed Anosov surface, in the large‑n limit. It combines strong convergence of permutation representations (via Magee–Puder–van Handel) with a detailed low‑frequency analysis using the spherical mean operator on the universal cover, all within Faure–Sjöstrand anisotropic Sobolev spaces to control resolvents. The main result shows that, for any compact set K in the half-plane Re z > δ0 (with δ0 = (1/2)Pr(−2ψ^u)), asymptotically almost surely there are no new Pollicott–Ruelle resonances in K as the degree grows, establishing a probabilistic spectral gap and highlighting the optimal regime in the hyperbolic case where a Laplacian–PR resonance correspondence is available. The work connects dynamical decay rates with random-cover spectral theory, offering methods that extend beyond constant-curvature settings to variable negative curvature and other random-surface models. The results have potential implications for quantitative decay of correlations on large random surfaces and deepen the link between geometric group representations, resonances, and stochastic models of geometry.
Abstract
Let $(M,g)$ be a closed Riemannian surface with Anosov geodesic flow. We prove the existence of a spectral gap for Pollicott--Ruelle resonances on random finite coverings of $M$ in the limit of large degree, which is expected to be optimal. The proof combines the recent strong convergence results of Magee, Puder and van Handel for permutation representations of surface groups with an analysis of the spherical mean operator on the universal cover of $M$.
