Charged gravastars admitting conformal motion

A.A Usmani,F Rahaman,Saibal Ray,K.K Nandi,Peter K.F Kuhfittig,Sk.A Rakib,Z Hasan

doi:10.1016/j.physletb.2011.06.001

Abstract

We propose a new model of a gravastar admitting conformal motion. While retaining the framework of the Mazur–Mottola model, the gravastar is assumed to be internally charged, with an exterior defined by a Reissner–Nordström instead of a Schwarzschild line element. The solutions, obtained by exploiting an assumed conformal Killing vector, involve (i) the interior region, (ii) the shell, and (iii) the exterior region of the sphere. Of these three cases the first one is of primary interest since the total gravitational mass here turns out to be an electromagnetic mass under some specific conditions. This suggests that the interior de Sitter vacuum of a charged gravastar is essentially an electromagnetic mass model that must generate gravitational mass which provides a stable configuration by balancing the repulsive pressure arising from charge with its attractive gravity to avert a singularity. Therefore the present model, like the Mazur–Mottola model, results in the construction of a compact astrophysical object, as an alternative to a black hole. We have also analyzed various other aspects such as the stress energy tensor in the thin shell and the entropy of the system.

Highlights

By extending the concept of Bose-Einstein condensate to gravitational systems, Mazur and Mottola [1, 2] have proposed a new solution for the endpoint of a gravitational collapse in the form of cold, dark, compact objects known as gravastars
We propose a new model of a gravastar admitting conformal motion by assuming a charged interior but with an exterior defined by a Reissner-Nordstrom line element instead of Schwarzschild
This paper discusses a new model of a gravastar admitting conformal motion, within the framework of the

Summary

INTRODUCTION

By extending the concept of Bose-Einstein condensate to gravitational systems, Mazur and Mottola [1, 2] have proposed a new solution for the endpoint of a gravitational collapse in the form of cold, dark, compact objects known as gravastars These contain an isotropic de Sitter vacuum in the interior, while the exterior is defined by a Schwarzschild geometry, separated by a thin shell of stiff matter of arbitrary total mass M. The presence of matter on the thin shell is required to achieve Building on this background, we propose a new model of a gravastar admitting conformal motion by assuming a charged interior but with an exterior defined by a Reissner-Nordstrom line element instead of Schwarzschild.

Interior region of the charged gravastar

Shell of the charged gravastar

THE STRESS ENERGY TENSOR IN THE THIN SHELL

ENTROPY WITHIN THE SHELL

THE UNKNOWN CONSTANTS ψ0 AND ψ1

CONCLUSIONS