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The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients of order three. We prove that this difference equation can be solved in general. Consequently we can find an exact solution to the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 A. J. John , S. D. Maharaj

We analyze the isothermal property in static fluid spheres within the framework of the modified $f(R, T)$ theory of gravitation. The equation of pressure isotropy of the standard Einstein theory is preserved however, the energy density and…

General Relativity and Quantum Cosmology · Physics 2018-09-26 Sudan Hansraj

We study the Einstein-Maxwell system of equations in spherically symmetric gravitational fields for static interior spacetimes. The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients. We…

General Relativity and Quantum Cosmology · Physics 2015-06-25 S. Thirukkanesh , S. D. Maharaj

We present exact solutions to the Einstein-Maxwell system of equations in spherically symmetric gravitational fields with a specified form of the electric field intensity. The condition of pressure isotropy yields a difference equation with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 S. D. Maharaj , K. Komathiraj

We find new classes of exact solutions to the Einstein-Maxwell system of equations for a charged sphere with a particular choice of the electric field intensity and one of the gravitational potentials. The condition of pressure isotropy is…

General Relativity and Quantum Cosmology · Physics 2009-03-19 K. Komathiraj , S. D. Maharaj

We present a general solution of the Einstein gravitational field equations for the static spherically symmetric gravitational interior spacetime of an isotropic fluid sphere. The solution is obtained by transforming the pressure isotropy…

General Relativity and Quantum Cosmology · Physics 2015-06-17 M. K. Mak , T. Harko

We analyse the gravitational behaviour of a relativistic heat conducting fluid in a shear-free spherically symmetric spacetime. We show that the isotropy of pressure is a consistency condition which realises a second order nonlinear…

General Relativity and Quantum Cosmology · Physics 2015-12-31 B. P. Brassel , S. D. Maharaj , G. Govender

We present an algorithm to generalize a plethora of well-known solutions to Einstein field equations describing spherically symmetric relativistic fluid spheres by relaxing the pressure isotropy condition on the system. By suitably fixing…

General Physics · Physics 2018-02-14 S. Thirukkanesh , F. C. Ragel , Ranjan Sharma , Shyam Das

The coupled system of the spherically symmetric Einstein--Maxwell differential equations is solved under two different source conditions: non-zero electric charge and pressure anisotropy. Expressions for the metric functions, and pressures…

General Relativity and Quantum Cosmology · Physics 2016-03-11 Ambrish M. Raghoonundun , David W. Hobill

New exact interior solutions to the Einstein field equations for anisotropic spheres are found. We utilise a procedure that necessitates a choice for the energy density and the radial pressure. This class contains the constant density model…

General Relativity and Quantum Cosmology · Physics 2009-11-11 M. Chaisi , S. D. Maharaj

The trace-free Einstein equations contain one equation less than the complete field equations. In a static and spherically symmetric spacetime, the number of field equations is thus reduced to two. The equation of pressure isotropy of…

General Relativity and Quantum Cosmology · Physics 2024-03-27 Sudan Hansraj , Chevarra Hansraj , Njabulo Mkhize , Abdelghani Errehymy , Christian G. Boehmer

We model a compact relativistic body with anisotropic pressures in the presence of an electric field. The equation of state is barotropic with a linear relationship between the radial pressure and the energy density. Simple exact models of…

General Relativity and Quantum Cosmology · Physics 2015-06-17 P. Mafa Takisa , S. D. Maharaj

We employ the gravitational decoupling approach for static and spherically symmetric systems to develop a simple and powerful method in order to a) continuously isotropize any anisotropic solution of the Einstein field equations, and b)…

General Relativity and Quantum Cosmology · Physics 2019-10-11 R. Casadio , E. Contreras , J. Ovalle , A. Sotomayor , Z. Stuchlick

By a choice of new variables the pressure isotropy condition for spherically symmetric static perfect fluid spacetimes can be made a quadratic algebraic equation in one of the two functions appearing in it. Using the other variable as a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Gyula Fodor

This paper formulates some new exact solutions to the field equations by means of minimal gravitational decoupling in the context of $f(\mathbb{R},\mathbb{T})$ gravity. For this purpose, we consider anisotropic spherical matter distribution…

General Relativity and Quantum Cosmology · Physics 2022-12-14 M. Sharif , Tayyab Naseer

I use the Newtonian equation of hydrostatic equilibrium for an isotropic fluid sphere to generate exact anisotropic solutions of Einstein's equations. The input function is simply the density. An infinite number of regular solutions are…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Kayll Lake

The Einstein-Maxwell equations with anisotropic pressures and electromagnetic field are studied with a polytropic equation of state. New exact solutions to the field equations are generated in terms of elementary functions. Special cases of…

General Relativity and Quantum Cosmology · Physics 2015-06-17 P. Mafa Takisa , S. D. Maharaj

We present a class of exact solutions of Einstein's gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by assuming a particular form of the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 T. Harko , M. K. Mak

Einstein field equations for anisotropic spheres are solved and exact interior solutions obtained. This paper extends earlier treatments to include anisotropic models which accommodate a wider variety of physically viable energy densities.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. Chaisi , S. D. Maharaj

Two distinct non-singular interior models that describe anisotropic spherical configurations are presented in this work. We develop the Einstein field equations and the associated mass function in accordance with a static spherical…

General Relativity and Quantum Cosmology · Physics 2025-10-10 M. Sharif , Tayyab Naseer , Hira Shadab
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