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Main Authors: Looi, Shi-Zhuo, Tohaneanu, Mihai
Format: Preprint
Published: 2022
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Online Access:https://arxiv.org/abs/2204.03626
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author Looi, Shi-Zhuo
Tohaneanu, Mihai
author_facet Looi, Shi-Zhuo
Tohaneanu, Mihai
contents This paper proves global existence and sharp pointwise decay for solutions to nonlinear wave equations satisfying the semilinear null condition, on a class of three-dimensional, asymptotically flat, and notably, non-stationary spacetimes. We consider nonlinearities satisfying a generalized null condition which does not necessarily retain its structure when commuted with vector fields. For sufficiently small initial data, and under the assumption that the underlying linear operator satisfies an integrated local energy decay estimate, we prove that solutions exist for all time and we establish sharp pointwise decay estimates for the solution $ϕ$ and its vector-fields. The solution itself decays as $|ϕ(t,x)| \lesssim \langle t+r \rangle^{-1} \langle t-r \rangle^{-1}$. This rate matches that of the nonlinear equation on a flat background. This rate is sharp, as this behavior holds already for certain time-dependent perturbations of the classical null form on Minkowski space, which we specify.
format Preprint
id arxiv_https___arxiv_org_abs_2204_03626
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Global existence and pointwise decay for nonlinear waves under the null condition
Looi, Shi-Zhuo
Tohaneanu, Mihai
Analysis of PDEs
This paper proves global existence and sharp pointwise decay for solutions to nonlinear wave equations satisfying the semilinear null condition, on a class of three-dimensional, asymptotically flat, and notably, non-stationary spacetimes. We consider nonlinearities satisfying a generalized null condition which does not necessarily retain its structure when commuted with vector fields. For sufficiently small initial data, and under the assumption that the underlying linear operator satisfies an integrated local energy decay estimate, we prove that solutions exist for all time and we establish sharp pointwise decay estimates for the solution $ϕ$ and its vector-fields. The solution itself decays as $|ϕ(t,x)| \lesssim \langle t+r \rangle^{-1} \langle t-r \rangle^{-1}$. This rate matches that of the nonlinear equation on a flat background. This rate is sharp, as this behavior holds already for certain time-dependent perturbations of the classical null form on Minkowski space, which we specify.
title Global existence and pointwise decay for nonlinear waves under the null condition
topic Analysis of PDEs
url https://arxiv.org/abs/2204.03626