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We consider an isothermal compressible fluid evolving on a cosmological background which may be either expanding or contracting toward the future. The Euler equations governing such a flow consist of two nonlinear hyperbolic balance laws…

Analysis of PDEs · Mathematics 2022-10-12 Yangyang Cao , Mohammad A. Ghazizadeh , Philippe G. LeFloch

In this paper we have obtained cosmological models for the static spherically symmetric spacetime with charged anisotropic fluid distribution in (n+2)-dimensions in context of Rosen's Bimetric General Relativity (BGR). An exact solution is…

General Physics · Physics 2017-05-12 A. H. Hasmani , D. N. Pandya

The purpose of this paper is to obtain exact solutions for charged anisotropic spherically symmetric matter configuration. For this purpose, we consider known solution for isotropic spherical system in the presence of electromagnetic field…

General Relativity and Quantum Cosmology · Physics 2018-07-04 M. Sharif , Sobia Sadiq

In a previously work, we undertook a static and anisotropic content in $f(T)$ theory and obtained new spherically symmetric solutions considering a constant torsion and some particular conditions for the pressure. In this paper, still in…

General Physics · Physics 2012-02-22 M. Hamani Daouda , Manuel E. Rodrigues , M. J. S. Houndjo

We discuss certain general features of type B warped spacetimes which have important consequences on the material content they may admit and its associated dynamics. We show that, for Warped B spacetimes, if shear and anisotropy are…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. Carot , L. A. Nunez

We study exact solutions of the Einstein-Maxwell equations for the interior gravitational field of static spherically symmetric charged compact spheres. The spheres consist of an anisotropic fluid with a charge distribution that gives rise…

General Relativity and Quantum Cosmology · Physics 2022-02-18 Krsna Dev

In this paper we study anisotropic spherical polytropes within the framework of general relativity. Using the anisotropic Tolman-Oppenheimer-Volkov (TOV) equations, we explore the relativistic anisotropic Lane-Emden equations. We find how…

General Relativity and Quantum Cosmology · Physics 2016-07-20 F. Shojai , M. Kohandel , A. Stepanian

This paper examines the general formalism and applications of isotropic as well as anisotropic polytropic stars in curvature-matter coupled gravity. For this purpose, we consider static spherical and Schwarzschild spacetimes in the interior…

General Relativity and Quantum Cosmology · Physics 2022-02-16 M. Sharif , Amal Majid , M. Shafaqat

In this work a class of interior solution for Einstein field equations corresponding to a spherically symmetric anisotropic fluid sphere has been obtained under the assumption that the cosmological constant is spatially variable. The…

General Relativity and Quantum Cosmology · Physics 2011-03-07 R. N. Tiwari , Saibal Ray

We examine a spherically-symmetric class of spacetimes carrying vacuum energy, while considering the influence of an external dark energy environment represented by a non-dynamical quintessence field. Our investigation focuses on a specific…

General Relativity and Quantum Cosmology · Physics 2024-05-06 Roberto Giambò , Orlando Luongo

We explore the effects of a positive cosmological constant on astrophysical and cosmological configurations described by a polytropic equation of state. We derive the conditions for equilibrium and stability of such configurations and…

Astrophysics · Physics 2008-11-26 Andres Balaguera-Antolinez , David F. Mota , Marek Nowakowski

We consider conditions for existence and stability of a static cosmological solution in quadratic gravity. It appears that such a solution for a Universe filled by only one type of perfect fluid is possible in a wide range of the equation…

General Relativity and Quantum Cosmology · Physics 2021-07-28 Daniel Muller , Alexey Toporensky

In this paper, we study the effects of modification of gravity on the problem of dynamical instability of the spherical relativistic anisotropic interiors. We have considered non-zero influence of expansion scalar throughout during the…

General Relativity and Quantum Cosmology · Physics 2018-07-17 Z. Yousaf , Kazuharu Bamba , M. Z. Bhatti , U. Farwa

A spherically symmetric charged ideal fluid solution of Einstein field equation is given in the presence of the cosmological constant and two well known example of this type of solution is presented. If the matter is confined in a region,…

General Relativity and Quantum Cosmology · Physics 2007-11-30 N. Ozdemir

In this paper, we have studied the stability of the cosmological models with dark energy and combination of matter fields and dark energy in an anisotropic space time. The pressure anisotropy along the spatial directions are derived and its…

General Relativity and Quantum Cosmology · Physics 2021-03-02 B. Mishra , Fakhereh Md. Esmaeili , Pratik P. Ray , S. K. Tripathy

We obtain a new anisotropic solution for spherically symmetric spacetimes by analysing of the Karmarkar embedding condition. For this purpose we construct a suitable form of one of the gravitational potentials to obtain a closed form…

General Physics · Physics 2017-06-28 S. K. Maurya , S. D. Maharaj

In this paper we are concerned with the effects of anisotropic pressure on the boundary conditions of anisotropic Lane-Emden equation and homology theorem. Some new exact solutions of this equation are derived. Then some of the theorems…

General Relativity and Quantum Cosmology · Physics 2015-07-10 F. Shojai , M. R. Fazel , A. Estepanian , M. Kohandel

We consider anisotropic fluids with directional pressures $p_i = w_i \rho$ ($\rho$ is the density, $w_i = $const, $i = 1,2,3$) as sources of gravity in stationary cylindrically symmetric space-times. We describe a general way of obtaining…

General Relativity and Quantum Cosmology · Physics 2019-06-19 S. V. Bolokhov , K. A. Bronnikov , M. V. Skvortsova

The paper deals with the static spherically symmetric wormhole solutions in $f(R)$-modified gravity theory with anisotropic matter field and for some particular choices for the shape functions. The present work may be considered as an…

General Relativity and Quantum Cosmology · Physics 2021-08-11 Bikram Ghosh , Saugata Mitra , Subenoy Chakraborty

The fluid models mentioned in the title are studied in a modified approach, based on two formulas for the mass function. All characteristics of the fluid are expressed through a master potential, satisfying an ordinary second order…

General Relativity and Quantum Cosmology · Physics 2011-04-21 B. V. Ivanov