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Main Authors: Tudor, Ciprian A, Zurcher, Jérémy
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2404.11147
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author Tudor, Ciprian A
Zurcher, Jérémy
author_facet Tudor, Ciprian A
Zurcher, Jérémy
contents Let $\left(u(t,x), t\geq 0, x\in \mathbb{R}^d\right)$ be the solution to the stochastic heat or wave equation driven by a Gaussian noise which is white in time and white or correlated with respect to the spatial variable. We consider the spatial average of the solution $F_{R}(t)= \frac{1}{σ_R}\int_{\vert x\vert \leq R} \left( u(t,x)-1\right) dx$, where $σ^2_R= \mathbf{E} \left(\int_{\vert x\vert \leq R} \left( u(t,x)-1\right) dx\right)^2$. It is known that, when $R$ goes to infinity, $F_R(t)$ converges in law to a standard Gaussian random variable $Z$. We show that the spatial average $F_R(t)$ is actually asymptotic independent by the solution itself, at any time and at any point in space, meaning that the random vector $(F_R(t), u(t, x_0))$ converges in distribution, as $R\to \infty$, to $(Z, u(t, x_0))$, where $Z$ is a standard normal random variable independent of $u(t, x_0)$. By using the Stein-Malliavin calculus, we also obtain the rate of convergence, under the Wasserstein distance, for this limit theorem.
format Preprint
id arxiv_https___arxiv_org_abs_2404_11147
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The spatial average of solutions to SPDEs is asymptotically independent of the solution
Tudor, Ciprian A
Zurcher, Jérémy
Probability
Let $\left(u(t,x), t\geq 0, x\in \mathbb{R}^d\right)$ be the solution to the stochastic heat or wave equation driven by a Gaussian noise which is white in time and white or correlated with respect to the spatial variable. We consider the spatial average of the solution $F_{R}(t)= \frac{1}{σ_R}\int_{\vert x\vert \leq R} \left( u(t,x)-1\right) dx$, where $σ^2_R= \mathbf{E} \left(\int_{\vert x\vert \leq R} \left( u(t,x)-1\right) dx\right)^2$. It is known that, when $R$ goes to infinity, $F_R(t)$ converges in law to a standard Gaussian random variable $Z$. We show that the spatial average $F_R(t)$ is actually asymptotic independent by the solution itself, at any time and at any point in space, meaning that the random vector $(F_R(t), u(t, x_0))$ converges in distribution, as $R\to \infty$, to $(Z, u(t, x_0))$, where $Z$ is a standard normal random variable independent of $u(t, x_0)$. By using the Stein-Malliavin calculus, we also obtain the rate of convergence, under the Wasserstein distance, for this limit theorem.
title The spatial average of solutions to SPDEs is asymptotically independent of the solution
topic Probability
url https://arxiv.org/abs/2404.11147