Compact stars with quadratic equation of state

Abstract

We provide new exact solutions to the EinsteinMaxwell system of equations for matter configurations with anisotropy and charge. The spacetime is static and spherically symmetric. A quadratic equation of state is utilised for the matter distribution. By specifying a particular form for one of the gravitational potentials and the electric field intensity we obtain new exact solutions in isotropic coordinates. In our general class of models, an earlier model with a linear equation of state is regained. For particular choices of parameters we regain the masses of the stars PSR J1614-2230, 4U 1608-52, PSR J1903+0327, EXO 1745-248 and SAX J1808.4-3658. A comprehensive physical analysis for the star PSR J1903+0327 reveals that our model is reasonable.

Anisotropic fluid spheres of embedding class one using Karmarkar condition

“…In recent times there has been made a considerable effort in modelling observed astrophysical objects in the presence of anisotropy. Some recent research papers addressing this physical feature include the work of Sharma and Ratanpal [4], Ngubelanga et al [5,6], Sunzu et al [7,8], Murad and Fatema [9,10] and Murad [11], and the references therein. The physical analyses contained in these treatments confirm the importance of including nonzero anisotropy in modelling astrophysical objects.…”

Anisotropic static spheres with linear equation of state in isotropic coordinates

“…It was shown that the equation of state (EOS) for strange stars developed by Dey et al (1998) can be approximated to a linear form, p = n(ρ − ρ s ) where n is a constant and ρ s is the surface density (Sharma and Maharaj 2007). The role played by a linear equation of state in the stability of charged compact objects was studied by Ngubelanga et al (2015b). By utilising isotropic coordinates, they were able to show that their solutions were wellbehaved and adequately described the physical features of a star like PSR J1614-2230.…”

“…This EOS was shown to adequately describe strange star candidates with the quadratic term playing a significant role in the predicted mass and radius profiles of these stellar objects (Maharaj and Takisa 2012;Takisa et al 2014). In a more recent study Ngubelanga et al (2015a) studied charged static spheres obeying a quadratic equation of state. By assuming a particular form for one of the gravitational potentials and specifying the behaviour of the electric field intensity, they were able to solve the Einstein-Maxwell system to obtain new exact solutions in isotropic coordinates.…”

Physical attributes of anisotropic compact stars in f(R, G) gravity

“…Staykov et al [42] used two different hadronic parameters and a strange matter EOS parameter to study the structure of rotating neutron stars. Quadratic EOS parameters have been used to study the properties of compact stars [46,47]. For the sake of simplicity, in this work we assume a linear EOS [48]:…”