Expected number of nodal components for cut-off fractional Gaussian fields - Archive ouverte HAL
Pré-Publication, Document De Travail Année : 2018

Expected number of nodal components for cut-off fractional Gaussian fields

Alejandro Rivera
  • Fonction : Auteur
  • PersonId : 1022750

Résumé

Let $({\mathcal{X}},g)$ be a closed Riemmanian manifold of dimension $n>0$. Let $\Delta$ be the Laplacian on ${\mathcal{X}}$, and let $(e_k)_k$ be an $L^2$-orthonormal and dense family of Laplace eigenfunctions with respective eigenvalues $(\lambda_k)_k$. We assume that $(\lambda_k)_k$ is non-decreasing and that the $e_k$ are real-valued. Let $(\xi_k)_k$ be a sequence of iid $\mathcal{N}(0,1)$ random variables. For each $L>0$ and $s\in{\mathbb{R}}$, possibly negative, set \[ f^s_L=\sum_{0<\lambda_j\leq L}\lambda_j^{-\frac{s}{2}}\xi_je_j\, . \] Then, $f_L^s$ is almost surely regular on its zero set. Let $N_L$ be the number of connected components of its zero set. If $s<\frac{n}{2}$, then we deduce that there exists $\nu=\nu(n,s)>0$ such that $N_L\sim \nu {Vol}_g({\mathcal{X}})L^{n/2}$ in $L^1$ and almost surely. In particular, ${\mathbb{E}}[N_L]\asymp L^{n/2}$. On the other hand, we prove that if $s=\frac{n}{2}$ then \[ {\mathbb{E}}[N_L]\asymp \frac{L^{n/2}}{\sqrt{\ln\left(L^{1/2}\right)}}\, . \] In the latter case, we also obtain an upper bound for the expected Euler characteristic of the zero set of $f_L^s$ and for its Betti numbers. In the case $s>n/2$, the pointwise variance of $f_L^s$ converges so it is not expected to have universal behavior as $L\rightarrow+\infty$.
Fichier principal
Vignette du fichier
main.pdf (377.44 Ko) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-01689153 , version 1 (21-01-2018)
hal-01689153 , version 2 (06-11-2018)

Identifiants

Citer

Alejandro Rivera. Expected number of nodal components for cut-off fractional Gaussian fields. 2018. ⟨hal-01689153v2⟩
82 Consultations
190 Téléchargements

Altmetric

Partager

More