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In this manuscript, we put forth a general scheme for defining initial value problems from Einstein's equations of General Relativity constrained by homogeneous and isotropic expansion. The cosmological models arising as solutions are…

General Relativity and Quantum Cosmology · Physics 2024-08-06 Leandro G. Gomes , Marcelo A. C. Nogueira , Lucas Ruiz dos Santos

Anisotropic spherically symmetric solutions within the framework of the Brans-Dicke theory are uncovered through a unique gravitational decoupling approach involving a minimal geometric transformation. This transformation effectively…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Kazuharu Bamba , M. Z. Bhatti , Z. Yousaf , Z. Shoukat

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

We find two new classes of exact solutions to the Einstein-Maxwell system of equations. The matter distribution satisfies a linear equation of state consistent with quark matter. The field equations are integrated by specifying forms for…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Jefta M. Sunzu , Sunil D. Maharaj , Subharthi Ray

A new class of solutions of Einstein field equations has been investigated for inhomogeneous cylindrically symmetric space-time with string source. To get the deterministic solution, it has been assumed that the expansion ($\theta$) in the…

General Relativity and Quantum Cosmology · Physics 2014-05-06 Anirudh Pradhan , A. K. Yadav , R. P. Singh , V. K. Singh

We find a new class of exact solutions to the Einstein-Maxwell equations which can be used to model the interior of charged relativistic objects. These solutions can be written in terms of special functions in general; for particular…

General Relativity and Quantum Cosmology · Physics 2013-01-01 K. Komathiraj , S. D. Maharaj

In this work, we present a class of relativistic and well-behaved solution to Einstein's field equations for anisotropic matter distribution. We perform our analysis by using the Buchdahl ansatz for the metric function grr. Three different…

General Relativity and Quantum Cosmology · Physics 2022-03-29 Amit Kumar Prasad , Jitendra Kumar

We provide new exact solutions to the Einstein-Maxwell system of equations which are physically reasonable. The spacetime is static and spherically symmetric with a charged matter distribution. We utilise an equation of state which is…

General Relativity and Quantum Cosmology · Physics 2015-06-12 S. D. Maharaj , P. Mafa Takisa

The aim of this paper is to study the formation of anisotropic compact stars in modified $f(R)$ theory of gravity, which is the generalization of the Einstein's gravity. To this end, we have used the solution of Krori and Barua to the…

General Physics · Physics 2016-05-04 M. Zubair , G. Abbas

There are a number of publications on relativistic objects dealing either with black holes or naked singularities in the center. Here we show that there exist static spherically symmetric solutions of Einstein equations with a strongly…

General Relativity and Quantum Cosmology · Physics 2024-08-27 O. S. Stashko , V. I. Zhdanov

Possibilities emerging out of the dynamical evolutions of collapsing systems are addressed in this thesis through analytical investigations of the highly non-linear Einstein Field Equations. Studies of exact solutions and their properties,…

General Relativity and Quantum Cosmology · Physics 2017-09-07 Soumya Chakrabarti

In the present article we find a new class of solutions of Einstein's field equations. It describes stationary, cylindrically symmetric spacetimes with closed timelike geodesics everywhere outside the symmetry axis. These spacetimes contain…

General Relativity and Quantum Cosmology · Physics 2010-04-20 Oyvind Gron , Steinar Johannesen

We set up in detail the general formalism to model polytropic general relativistic stars with anisotropic pressure. We shall consider two different possible polytropic equations, all of which yield the same Lane-Emden equation in the…

General Relativity and Quantum Cosmology · Physics 2015-06-17 L. Herrera , W. Barreto

We find a set of spacetime solutions whose rotation curves approach a flat profile at large radii, as observed for spiral galaxies. The associated stress-energy tensor reflects a positive mass and anisotropic pressure. The spatially…

General Relativity and Quantum Cosmology · Physics 2025-10-24 Sandipan Sengupta

Owed to their compactness, neutron stars involve strong gravity and extreme density physics. Nevertheless, at present, there are a variety of problems where progress (at least conceptually) can be made in the context of weak gravity.…

General Relativity and Quantum Cosmology · Physics 2023-03-02 Nils Andersson , Fabian Gittins , Shanshan Yin , Rodrigo Panosso Macedo

In a series of articles we describe a novel class of geometrical models of relativistic stars. Our approach to the static spherically symmetric solutions of Einstein equations is based on a careful physical analysis of radial gauge…

Astrophysics · Physics 2007-05-23 P. P. Fiziev

We prove well-posedness of the initial value problem for the Einstein equations for spatially-homogeneous cosmologies with data at an isotropic cosmological singularity, for which the matter content is either a cosmological constant with…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Paul Tod

We construct spherically symmetric, static solutions to the Einstein-Vlasov system with non-vanishing cosmological constant $\Lambda$. The results are divided as follows. For small $\Lambda>0$ we show existence of globally regular solutions…

General Relativity and Quantum Cosmology · Physics 2014-09-19 Håkan Andréasson , David Fajman , Maximilian Thaller

In this paper, we generate an exact anisotropic gravastar model using gravitational decoupling technique through minimal geometric deformation in the framework of $f(\Re, {T}^{2})$ gravity. This novel model explains an ultra-compact stellar…

General Relativity and Quantum Cosmology · Physics 2023-04-17 M. Sharif , Saba Naz

We model a charged anisotropic relativistic star with a quadratic equation of state. Physical features of an exact solution of the Einstein-Maxwell system are studied by incorporating the effect of the nonlinear term from the equation of…

General Relativity and Quantum Cosmology · Physics 2015-06-23 P. Mafa Takisa , S. D. Maharaj , Subharthi Ray