Central limit theorems for nonlinear stochastic wave equations in dimension three
Masahisa Ebina
TL;DR
This paper addresses Gaussian fluctuations for spatial averages of the 3D nonlinear stochastic wave equation driven by Gaussian noise with spatial covariance. Using the Malliavin–Stein framework, it proves that the properly normalized spatial average $F_R(t)$ converges to a Gaussian limit as the observation radius $R$ grows, under both a short-range Dalang condition ($\gamma\in L^1$ with $\gamma>0$) and a long-range Riesz kernel regime ($\gamma(x)=|x|^{-\beta}$, $0<\beta<2$). It further establishes functional central limit theorems for the processes $t\mapsto F_R(t)$, identifying the limiting Gaussian processes and their covariance structures, and providing nondegeneracy and convergence-rate insights. The results rely on a Picard-approximation approach tailored to the 3D wave kernel, together with Malliavin derivatives and variance bounds that bridge to Gaussian limits, and they extend CLTs for spatial averages to the physically relevant dimension three with both short- and long-range spatial correlations.
Abstract
In this paper, we consider three-dimensional nonlinear stochastic wave equations driven by the Gaussian noise which is white in time and has some spatial correlations. Using the Malliavin-Stein's method, we prove the Gaussian fluctuation for the spatial average of the solution under the Wasserstein distance in the cases where the spatial correlation is given by an integrable function and by the Riesz kernel. In both cases we also establish functional central limit theorems.
