Stable Bounded Excursion Gravastars with Regular Black Holes

TL;DR

This study investigates the stability of bounded excursion gravastars within regular black hole backgrounds, identifying conditions under which such structures can exist, and highlighting the influence of matter properties and geometries on their stability.

Contribution

It introduces a model for stable bounded excursion gravastars in regular black hole backgrounds, analyzing the effects of matter equations of state and geometric configurations.

Findings

Stable gravastars exist with de Sitter interior and regular black hole exterior.

No stable bounded excursion gravastars found with flat interior and regular exterior geometries.

Physical parameters critically determine the stability of these compact objects.

Abstract

This paper explores the possible existence of stable regions of bounded excursion gravastars in the background of regular black holes (Bardeen and Bardeen-de Sitter black holes). For this purpose, we match internal de Sitter geometry with an external regular black hole through an intermediate shell with an equation of state. The matter surface located at the shell greatly affects the dynamical configuration of the shell. We consider stiff and dust fluids to discuss the outcomes of the developed structures. We then determine the critical values of physical parameters at which the shell neither collapses nor expands for both cases with different choices of external and internal geometries. It is found that there does not exist any possible region of stable bounded excursion gravastar for the interior flat and exterior regular geometries. However, the stable bounded excursion gravastar is obtained for the interior de Sitter and exterior regular black holes with a suitable choice of physical parameters for both stiff and dust shells. We conclude that the possibility of the existence of both bounded excursion gravastars as well as black holes cannot be excluded in the dynamical model.