English

Looping directions and integrals of eigenfunctions over submanifolds

Analysis of PDEs 2017-10-03 v3

Abstract

Let (M,g)(M,g) be a compact nn-dimensional Riemannian manifold without boundary and eλe_\lambda be an L2L^2-normalized eigenfunction of the Laplace-Beltrami operator with respect to the metric gg, i.e Δgeλ=λ2eλ and eλL2(M)=1. -\Delta_g e_\lambda = \lambda^2 e_\lambda \qquad \text{ and } \qquad \| e_\lambda \|_{L^2(M)} = 1. Let Σ\Sigma be a dd-dimensional submanifold and dμd\mu a smooth, compactly supported measure on Σ\Sigma. It is well-known (e.g. proved by Zelditch in far greater generality) that Σeλdμ=O(λnd12). \int_\Sigma e_\lambda \, d\mu = O(\lambda^\frac{n-d-1}{2}). We show this bound improves to o(λnd12)o(\lambda^\frac{n-d-1}{2}) provided the set of looping directions, LΣ={(x,ξ)SNΣ:Φt(x,ξ)SNΣ for some t>0} \mathcal{L}_{\Sigma} = \{ (x,\xi) \in SN^*\Sigma : \Phi_t(x,\xi) \in SN^*\Sigma \text{ for some } t > 0 \} has measure zero as a subset of SNΣSN^*\Sigma, where here Φt\Phi_t is the geodesic flow on the cosphere bundle SMS^*M and SNΣSN^*\Sigma is the unit conormal bundle over Σ\Sigma.

Keywords

Cite

@article{arxiv.1706.06717,
  title  = {Looping directions and integrals of eigenfunctions over submanifolds},
  author = {Emmett L. Wyman},
  journal= {arXiv preprint arXiv:1706.06717},
  year   = {2017}
}
R2 v1 2026-06-22T20:24:42.463Z