Role of pressure anisotropy on relativistic compact stars

Abstract

We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina and Orlyanskii [Ukr. Phys. J. 36, 885 (1991)] type in order to solve the Einstein field equations. An additional prescription we make is that the pressure anisotropy parameter takes the functional form proposed by Lake [Phys. Rev. D 67, 104015 (2003)]. Specifying these two geometric quantities allows for further analysis to be carried out in determining unknown constants and obtaining a limit of the mass-radius diagram, which adequately describes compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium and the stability of such compact objects. Then, we investigate other physical features of this models, such as the energy conditions, speeds of sound and compactness of the star in detail and show that our results satisfy all the required elementary conditions for a physically acceptable stellar model. The results obtained are useful in analyzing the stability of other anisotropic compact objects like white dwarfs, neutron stars, and gravastars.

Anisotropic relativistic fluid spheres: an embedding class I approach

“…(ω r = p r /ρ) and (ω t = p t /ρ) are less than 1, proving Zeldovich's condition is satisfies everywhere inside the compact object. Furthermore, in Table 1 we have shown the possible values of the physical parameters a, A and B using parameters values of the compact star SAX J1808.4-3658 with mass Table 2 shows that the central energy density is within this range, which is in complete agreement with many other reported results in the literature [45][46][47][48][49][50][51][52][53][54][55][57][58][59][60][61][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80]. Figure 6 clearly shows that our stellar system fulfills all the energy conditions which are a basic condition for a compact astrophysical structure to be physically acceptable.…”

Anisotropic neutron stars and perfect fluid’s energy conditions

“…Here, σ is the difference between radial ( p) and tangential pressure(q) (known as anisotropic factors), g μν is space-time metric, u μ is fluid 4-velocity, and k μ is velocity in radial direction where the relation u μ k μ = 0 is fulfilled. And also for the general spherically symmetric static space-time geometry, the metric reads ds 2 = −e 2ν dt 2 + e 2λ dr 2 + r 2 (dθ 2 + sin 2 θ dφ 2 ), (9) to calculate Einstein field tensor G μν . By equating G μν and T μν , we can obtain the TOV equation for anisotropic NSs as follows, [2] d…”

“…(please see Refs. [1][2][3][4][5][6][7][8][9] and the references therein for reviews). The discussions of the relation of the instability of anisotropic stars with perfect fluid energy condition have been reported in Refs.…”

Charged anisotropic compact star in f(R,T) gravity: A minimal geometric deformation gravitational decoupling approach

“…Respect to the inclusion of electric charge Bonnors [76] pioneering work opened the door to this interesting research area. At present, several papers available in the literature address the study of compact objects describing anisotropic matter distributions [77] (and references contained therein). Recently, a simpler but powerful mechanism developed by Ovalle and his collaborators to introduce anisotropic behavior in the stellar matter [78,79], has been proved to be a versatile method.…”