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We study spherically symmetric geometries made of anisotropic perfect fluid based on general relativity. The purpose of the work is to find and classify black hole solutions in closed spacetime. In a general setting, we find that a static…

General Relativity and Quantum Cosmology · Physics 2017-10-04 Hyeong-Chan Kim

We study the homogeneous but anisotropic Bianchi type-V cosmological model with time-dependent gravitational and cosmological "constants". Exact solutions of the Einstein field equations (EFEs) are presented in terms of adjustable…

General Relativity and Quantum Cosmology · Physics 2018-07-30 Alnadhief H. A. Alfedeel , Amare Abebe , Hussam M. Gubara

We present a novel homogeneous and geometrically flat exact solution of Einstein's General Relativity equations for an ideal fluid. The solution, which describes an expanding/contracting hypercylinder, fits well with the observational…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-05 David H. Oaknin

In this paper, we have introduced new viable solutions of Einstein-Maxwell field equations by incorporating the features of anisotropic matter distribution in the realm of General theory of Relativity ($GR$). For this procurement, we have…

General Relativity and Quantum Cosmology · Physics 2023-03-29 H. Nazar , M. Azam , G. Abbas , R. Ahmed , R. Naeem

In the present work we have investigated a new anisotropic solution for polytropic star in the framework of $4D$ Einstein-Gauss-Bonnet (EGB) gravity. The possibility of determining the masses and radii of compact stars which puts some…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Ksh. Newton Singh , S. K. Maurya , Piyali Bhar , Riju Nag

We review analytical solutions of the Einstein equations which are expressed in terms of elementary functions and describe Friedmann-Lema\^itre-Robertson-Walker universes sourced by multiple (real or effective) perfect fluids with constant…

General Relativity and Quantum Cosmology · Physics 2021-12-15 Valerio Faraoni , Sonia Jose , Steve Dussault

A spherically symmetric comoving fluid solution of Einstein's equations is adapted for cosmological application by extending the geometry of standard FRW cosmology using a generalised curvature term. The resulting model retains many of the…

General Relativity and Quantum Cosmology · Physics 2009-09-15 Ron Wiltshire

The Einstein field equations are derived for a static cylindrically symmetric spacetime with elastic matter. The equations can be reduced to a system of two nonlinear ordinary differential equations and we present analytical and numerical…

General Relativity and Quantum Cosmology · Physics 2014-03-25 I. Brito , J. Carot , F. C. Mena , E. G. L. R. Vaz

A simple generalization to Einstein's general relativity (GR) was recently proposed which allows a correction term $T_{\alpha\beta}T^{\alpha\beta}$ in the action functional of the theory. This theory is called Energy-Momentum Squared…

General Relativity and Quantum Cosmology · Physics 2018-07-25 Nasrin Nari , Mahmood Roshan

The popularity of the Finch-Skea ansatz to describe relativistic stellar model have encouraged us to study the analytic solutions of the Einstein field equation. We have presented a class of exact solutions to the field equations after…

General Relativity and Quantum Cosmology · Physics 2021-07-14 Shyam Das , Koushik Chakraborty , Lipi Baskey , Saibal Ray

We discuss numerical solutions of Einstein's field equation describing static, spherically symmetric conglomerations of a photon gas. These equations imply a back reaction of the metric on the energy density of the photon gas according to…

General Relativity and Quantum Cosmology · Physics 2015-06-25 H. -J. Schmidt , F. Homann

We provide new exact solutions to the Einstein-Maxwell 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…

General Relativity and Quantum Cosmology · Physics 2016-01-06 Sifiso A. Ngubelanga , Sunil D. Maharaj , Subharthi Ray

When solving the equations of General Relativity in a symmetric sector, it is natural to consider the same symmetry for the geometry and stress-energy. This implies that for static and isotropic spacetimes, the most general natural…

General Relativity and Quantum Cosmology · Physics 2015-05-14 Tomasz Konopka

We present a class of new relativistic solutions with anisotropic fluid for compact stars in hydrostatic equilibrium. The interior space-time geometry considered here for compact objects are described by parameters namely, $\lambda$, $k$,…

General Relativity and Quantum Cosmology · Physics 2016-03-25 Bikash Chandra Paul , Rumi Deb

In this article we deduce two new exact solutions of Einstein's equations for eternal black holes, now related to stiff matter, one `static' and another rotating (stationary like the Kerr one), thus the number of these eternal solutions…

General Relativity and Quantum Cosmology · Physics 2012-10-19 Nikolai V. Mitskievich

We interpret the exact solutions previously obtained for spherically symmetric shells of liquid fluid in General Relativity in terms of the energies involved. We show that a certain parameter that was introduced into the solutions by the…

General Relativity and Quantum Cosmology · Physics 2021-04-16 Jorge L. deLyra

We study the Einstein equations of the static spherically symmetric anisotropic fluid system in curvature coordinates to find algorithms that generate all solutions and all solutions that are regular at the center. All possible combinations…

General Relativity and Quantum Cosmology · Physics 2021-09-01 M M Akbar , R Solanki

We introduce a proposal to modify Einstein's equations by embedding them in a larger symmetric hyperbolic system. The additional dynamical variables of the modified system are essentially first integrals of the original constraints. The…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Othmar Brodbeck , Simonetta Frittelli , Peter Huebner , Oscar A. Reula

In this work, we report a new exact solution of Einstein's field equations for static spherically symmetric anisotropic matter distributions on the background of paraboloidal spacetime by assuming a quadratic equation of state. The model…

General Relativity and Quantum Cosmology · Physics 2025-08-25 B S Ratanpal , Bhavesh Suthar

The Einstein-Vlasov-Fokker-Planck system describes the kinetic diffusion dynamics of self-gravitating particles within the Einstein theory of general relativity. We study the Cauchy problem for spatially homogeneous and isotropic solutions…

Analysis of PDEs · Mathematics 2017-10-30 Simone Calogero , Stephen Pankavich