Uniform bounds for period integrals and sparse equidistribution

Abstract

Let $M=\Gamma \backslash \mathrm{PSL}(2,\mathbb{R})$ be a compact manifold, and let $f\in C^{\infty }(M)$ be a function of zero average. We use spectral methods to get uniform (i.e. independent of spectral gap) bounds for twisted averages of $f$ along long horocycle orbit segments. We apply this to obtain an equidistribution result for sparse subsets of horocycles on $M$.

arXiv comment23 pages