Charged gravastar model in Rastall theory of gravity

Abstract

Gravastars are considered as exotic compact objects, may be found at the end of gravitational collapse of massive stars, to resolve the complexities of black holes. In this paper, we analyse the role of charge on the possible formation of an isotropic spherically symmetric gravastar configuration in the framework of Rastall gravity. Gravastar contains three distinct layers viz. (i) Interior region characterised by the equation of state, $p=-\rho$, which defines the repulsive outward pressure in the radial direction at all points on the thin shell, (ii) Thin shell contains an ultra-relativistic stiff fluid, which is denoted by the equation of state $p=\rho$ following Zel'dovich's criteria for a cold baryonic universe, and can withstand the repulsive pressure exerted by the interior region, and (iii) Exterior region which is the vacuum space-time represented by the Reissner-Nordström solution. Following above specifications, we construct and analyse charged gravastar model in the framework of Rastall gravity, which represents several salient features. The basic physical attributes, viz. proper length, energy, entropy and equation of state parameter of the shell are investigated. In this model, it is interesting to note that for a large radius of the hypersurface (R), the equation of state parameter of the thin shell corresponds to a dark energy equation of state with $W\left(R\right)\to -1$. However, for small value of R, $W\left(R\right)\to 0$, defines dust shell. The stability of the model is ensured through the study of gravitational surface redshift and maximisation of shell entropy within the framework of Rastall theory of gravity.