Study of gravastars in Rastall gravity

Abstract

Gravastars have been considered as a feasible alternative to black holes in the past couple of decades. Stable models of gravastar have been studied in many of the alternative gravity theories besides standard General Relativity (GR). The Rastall theory of gravity is a popular alternative to GR, specially in the cosmological and astrophysical context. Here, we propose a stellar model under the Rastall gravity following Mazur-Mottola's [1,2] conjecture. The gravastar consists of three regions, viz., (I) Interior region, (II) Intermediate shell region, and (III) Exterior region. The pressure within the interior core region is assumed with a constant negative matter-energy density which provides a repulsive force over the entire thin shell region. The shell is assumed to be made up of fluid of ultrarelativistic plasma which follows the Zel'dovich's conjecture of stiff fluid [3,4]. It is also assumed that the pressure is proportional to the matter-energy density according to Zel'dovich's conjecture, which cancel the repulsive force exerted by the interior region. The exterior region is completely vacuum which is described by the Schwarzschild-de Sitter solution. Under all these specifications we obtain a set of exact and singularity-free solutions of the gravastar model presenting several physically valid features within the framework of Rastall gravity. The physical properties of the shell region namely, the energy density, proper length, total energy and entropy are explored. The stability of the gravastar model is investigated using the surface redshift against the shell thickness and maximizing the entropy of the shell within the framework of Rastall gravity.

Stable Charged Gravastar model in Cylindrically Symmetric Space-time

“…Similarly, we match the thin shell and the exterior region at r = r 2 , to find the range of the outer radius hence the range of thickness (r 2 − r 1 ) of charged gravastar. We take the interior radius R 1 = 10km [12].…”

Kuchowicz gravastars in the braneworld formalism

“…Also, we could see that both energy density and isotropic pressure do not suffer from the central singularity, which is common for gravastars models with non-singular metric potentials. Consequently, while we already defined stress-energy tensor components, we finally could also calculate the total interior region mass from the formula [31]:…”

Stable three-dimensional (un)charged AdS gravastars in gravity’s rainbow

“…[92]. Ghosh et al [93] extracted the gravastar solutions in Rastall gravity. Considering F(R, G) theory of gravity, the gravastar model has been evaluated in Ref.…”