Stable gravastars - an alternative to black holes?

TL;DR

This paper investigates the stability of gravastars, alternative compact objects to black holes, by constructing a simplified model that allows for a full dynamical stability analysis, finding some configurations to be stable.

Contribution

It provides a simplified, fully analyzable model of gravastars to assess their dynamic stability against perturbations, advancing the understanding of their viability as black hole alternatives.

Findings

Certain equations of state lead to stable gravastar configurations

The model demonstrates the possibility of stable gravastars under specific conditions

Dynamic stability depends on the properties of the transition layer

Abstract

The "gravastar" picture developed by Mazur and Mottola is one of a very small number of serious challenges to our usual conception of a "black hole". In the gravastar picture there is effectively a phase transition at/ near where the event horizon would have been expected to form, and the interior of what would have been the black hole is replaced by a segment of de Sitter space. While Mazur and Mottola were able to argue for the thermodynamic stability of their configuration, the question of dynamic stability against spherically symmetric perturbations of the matter or gravity fields remains somewhat obscure. In this article we construct a model that shares the key features of the Mazur-Mottola scenario, and which is sufficiently simple for a full dynamical analysis. We find that there are some physically reasonable equations of state for the transition layer that lead to stability.