Stable Gravastars of Anisotropic Dark Energy

Abstract

Dynamical models of prototype gravastars made of phantom 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 (or phantom) fluid, and the external Schwarzschild region. It is found that in some cases the models represent the "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 or normal stars. In the phase space, the region for the "bounded excursion" gravastars is very small in comparison to that of black holes, but not empty, as found in our previous papers. Therefore, although the existence of gravastars can not be completely excluded from current analysis, the opposite is not possible either, that is, even if gravastars exist, they do not exclude the existence of black holes.

35 pages, 43 figures, added some clarifying texts and corrected some typos, accepted for publication in JCAP

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• Gravastars and Black Holes of Anisotropic Dark Energy
• Charge Gravastars in $f(T)$ Modified Gravity
• How the Charge Can Affect the Formation of Gravastars
• Stable Bounded Excursion Gravastars with Regular Black Holes
• Stability of $d$-dimensional Gravastars with Variable Equation of State
• How the Cosmological Constant Affects Gravastar Formation
• Radiating Gravastars
• Stability analysis of Lower Dimensional Gravastars in noncommutative geometry
• Charged Gravastar in a Dark Energy Universe
• Dynamical Evolution of an Unstable Gravastar with Zero Mass