Generically sharp decay and blowing up at infinity for a weak null wave system

Fuente: arXiv
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Autori principali: Dong, Shijie, Ma, Siyuan, Ma, Yue, Yuan, Xu
Natura: Preprint
Pubblicazione: 2026
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author Dong, Shijie
Ma, Siyuan
Ma, Yue
Yuan, Xu
author_facet Dong, Shijie
Ma, Siyuan
Ma, Yue
Yuan, Xu
contents We study a system of semilinear wave equations satisfying the weak null condition, which can be regarded as a simplified model for the Einstein vacuum equations. The main objective is to establish precise pointwise decay estimates, as both lower and upper bounds of decay, for small data solutions. Specifically, we show that the difference between the solution and its leading-order term is dominated by lower-order terms that decay faster in the retarded time variable $u=t-r$. Moreover, we prove that these pointwise decay estimates are sharp for a generic class of small initial data decaying sufficiently fast. As applications of these estimates, we demonstrate that the energy of one component of the solution admits a lower bound that generically grows to infinity as $t\to +\infty$, which can be interpreted as ``blowing up at infinity." Furthermore, we verify that this component generically exhibits an energy cascade from high to low frequencies.
format Preprint
id arxiv_https___arxiv_org_abs_2602_22749
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Generically sharp decay and blowing up at infinity for a weak null wave system
Dong, Shijie
Ma, Siyuan
Ma, Yue
Yuan, Xu
Analysis of PDEs
Mathematical Physics
We study a system of semilinear wave equations satisfying the weak null condition, which can be regarded as a simplified model for the Einstein vacuum equations. The main objective is to establish precise pointwise decay estimates, as both lower and upper bounds of decay, for small data solutions. Specifically, we show that the difference between the solution and its leading-order term is dominated by lower-order terms that decay faster in the retarded time variable $u=t-r$. Moreover, we prove that these pointwise decay estimates are sharp for a generic class of small initial data decaying sufficiently fast. As applications of these estimates, we demonstrate that the energy of one component of the solution admits a lower bound that generically grows to infinity as $t\to +\infty$, which can be interpreted as ``blowing up at infinity." Furthermore, we verify that this component generically exhibits an energy cascade from high to low frequencies.
title Generically sharp decay and blowing up at infinity for a weak null wave system
topic Analysis of PDEs
Mathematical Physics
url https://arxiv.org/abs/2602.22749