Gravastars and Black Holes of Anisotropic Dark Energy

TL;DR

This paper models gravastars made of anisotropic dark energy, demonstrating stable oscillating configurations and black hole formation with dark energy interiors and shells, highlighting the role of anisotropy in their development.

Contribution

It introduces the first model of gravastars and black holes with both interior and shell composed solely of dark energy, emphasizing anisotropy effects.

Findings

Stable oscillating gravastars with dark energy interiors.

Black hole formation with dark energy shells.

Anisotropy sign influences gravastar formation.

Abstract

Dynamical models of prototype gravastars made of anisotropic dark energy are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\gamma)\sigma$ divides the whole spacetime into two regions, the internal region filled with a dark energy fluid, and the external Schwarzschild region. The models represent "bounded excursion" stable gravastars, where the thin shell is oscillating between two finite radii, while in other cases they collapse until the formation of black holes. Here we show, for the first time in the literature, a model of gravastar and formation of black hole with both interior and thin shell constituted exclusively of dark energy. Besides, the sign of the parameter of anisotropy ($p_t - p_r$) seems to be relevant to the gravastar formation. The formation is favored when the tangential pressure is greater than the radial pressure, at least in the neighborhood of the isotropic case ($\omega=-1$).