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arXiv · 2212.11420

Nonradial stability of expanding Goldreich-Weber stars

Mahir Hadžić·Juhi Jang·King Ming Lam
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Abstract

Goldreich-Weber solutions constitute a finite-parameter of expanding and collapsing solutions to the mass-critical Euler-Poisson system. Two subclasses of this family correspond to compactly supported density profiles suitably modulated by the dynamic radius of the star that expands at the self-similar rate $\lambda(t)_{t\to\infty}\sim t^{\frac23}$ and linear rate $\lambda(t)_{t\to\infty}\sim t$ respectively. We prove two results: any linearly expanding Goldreich-Weber star is nonlinearly stable, while any given self-similarly expanding Goldreich-Weber star is codimension-4 nonlinearly stable against irrotational perturbations. The codimension-4 condition in the latter result is optimal and reflects the presence of 4 unstable directions in the linearised dynamics in self-similar coordinates, which are induced by the conservation of the energy and the momentum. This result can be viewed as a codimension-1 nonlinear stability of the moduli space of self-similarly expanding Goldreich-Weber stars against irrotational perturbations.

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Mahir Hadžić, Juhi Jang, King Ming Lam. 2022-12-22. Nonradial stability of expanding Goldreich-Weber stars. https://arxiv.org/abs/2212.11420

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