Gravitational collapse of a circularly symmetric star

TL;DR

This paper studies the gravitational collapse of a circularly symmetric star with outgoing radiation in 2+1-dimensional anti-de Sitter space, revealing conditions for black hole formation or complete evaporation before singularity formation.

Contribution

It introduces a model for star collapse in 2+1D AdS spacetime with a dynamic exterior metric and analyzes the conditions leading to black hole formation or evaporation.

Findings

Collapse can result in BTZ black hole formation.

Under certain conditions, the star's mass-energy evaporates before singularity.

Initial conditions determine the collapse outcome.

Abstract

We investigate the collapse of a circularly symmetric star with outgoing radiation in ($2+1$)-dimensional anti-de Sitter spacetime. The exterior spacetime of the collapsing star is assumed to be described by the non-static generalization of the Ba\~nados, Teitelboim and Zanelli [{\em Phys. Rev. Lett.} {\bf 69} (1992) 1849 ] metric. Making use of the junction conditions joining smoothly the interior and the exterior spacetimes across the boundary, we analyze the impacts of various factors on the evolution of the star which begins its collapse from an initial static configuration. In particular, depending on initial conditions, two possible outcomes of the collapse process are shown: (i) formation of a BTZ black hole, and (ii) evaporation of all mass-energy even before the singularity is reached.