Asymptotics for the spectral function on Zoll manifolds

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Hauptverfasser: Canzani, Yaiza, Galkowski, Jeffrey, Keeler, Blake
Format: Preprint
Veröffentlicht: 2022
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author Canzani, Yaiza
Galkowski, Jeffrey
Keeler, Blake
author_facet Canzani, Yaiza
Galkowski, Jeffrey
Keeler, Blake
contents Let $(M,g)$ be a Zoll manifold, i.e., a smooth, compact, Riemannian manifold without boundary all of whose geodesics are closed with a minimal common period $T$. The positive definite Laplace-Beltrami operator has eigenvalues $\{λ_j^2\}_j$ which cluster around $ν^2_\ell$ for some sequence $ν_\ell\to \infty$. This article is concerned with the number of $λ_j$ in a window of fixed size $\mathrm{w}$ around $ν_\ell$, denoted by $\mathbf{N}(ν_\ell,\mathrm{w}):=\#\{j\,:\, λ_j\in[ν_\ell-\mathrm{w},ν_\ell+\mathrm{w}]\}.$ When the set of trajectories with period smaller than $T$ has zero measure, there is $c_{n}>0$, depending only on $n=\operatorname{dim} M$, such that $$ \mathbf{N}(ν_\ell,\mathrm{w}) =c_n\operatorname{vol}_g(M)ν_{\ell}^{n-1}+o(ν_{\ell}^{n-1}), $$ as $\ell \to \infty$. However, for a general Zoll manifold this may not be the case. We show that, nevertheless, there is $N>0$, independent of $\ell$, such that $$ \sum_{j=0}^{N-1}\mathbf{N}(ν_{\ell+j},\mathrm{w})= c_nN\operatorname{vol}_g(M)ν_{\ell}^{n-1}+o(ν_{\ell}^{n-1}), $$ as $\ell \to \infty$. In addition to asymptotics for the counting function, we study the kernel of the spectral projector for the Laplacian, $Π_{\ell,\mathrm{w}}(x,y)$ onto the spectrum in ${\bigcup_{j=0}^{N-1}[ν_{\ell+j}-\mathrm{w},ν_{\ell+j}+\mathrm{w}]}$. We show that for $x$ and $y$ in a shrinking neighborhood of a point with few loops of length smaller than $T$, $Π_{\ell,\mathrm{w}}(x,y)$ and its derivatives have the same asymptotics as those on the round sphere and flat torus.
format Preprint
id arxiv_https___arxiv_org_abs_2211_09644
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Asymptotics for the spectral function on Zoll manifolds
Canzani, Yaiza
Galkowski, Jeffrey
Keeler, Blake
Analysis of PDEs
Spectral Theory
35P20, 58J50
Let $(M,g)$ be a Zoll manifold, i.e., a smooth, compact, Riemannian manifold without boundary all of whose geodesics are closed with a minimal common period $T$. The positive definite Laplace-Beltrami operator has eigenvalues $\{λ_j^2\}_j$ which cluster around $ν^2_\ell$ for some sequence $ν_\ell\to \infty$. This article is concerned with the number of $λ_j$ in a window of fixed size $\mathrm{w}$ around $ν_\ell$, denoted by $\mathbf{N}(ν_\ell,\mathrm{w}):=\#\{j\,:\, λ_j\in[ν_\ell-\mathrm{w},ν_\ell+\mathrm{w}]\}.$ When the set of trajectories with period smaller than $T$ has zero measure, there is $c_{n}>0$, depending only on $n=\operatorname{dim} M$, such that $$ \mathbf{N}(ν_\ell,\mathrm{w}) =c_n\operatorname{vol}_g(M)ν_{\ell}^{n-1}+o(ν_{\ell}^{n-1}), $$ as $\ell \to \infty$. However, for a general Zoll manifold this may not be the case. We show that, nevertheless, there is $N>0$, independent of $\ell$, such that $$ \sum_{j=0}^{N-1}\mathbf{N}(ν_{\ell+j},\mathrm{w})= c_nN\operatorname{vol}_g(M)ν_{\ell}^{n-1}+o(ν_{\ell}^{n-1}), $$ as $\ell \to \infty$. In addition to asymptotics for the counting function, we study the kernel of the spectral projector for the Laplacian, $Π_{\ell,\mathrm{w}}(x,y)$ onto the spectrum in ${\bigcup_{j=0}^{N-1}[ν_{\ell+j}-\mathrm{w},ν_{\ell+j}+\mathrm{w}]}$. We show that for $x$ and $y$ in a shrinking neighborhood of a point with few loops of length smaller than $T$, $Π_{\ell,\mathrm{w}}(x,y)$ and its derivatives have the same asymptotics as those on the round sphere and flat torus.
title Asymptotics for the spectral function on Zoll manifolds
topic Analysis of PDEs
Spectral Theory
35P20, 58J50
url https://arxiv.org/abs/2211.09644