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A linear relationship between the Hubble expansion parameter and the time derivative of the scalar field is assumed in order to derive exact analytic cosmological solutions to Einstein's gravity with two fluids: a barotropic perfect fluid…

General Relativity and Quantum Cosmology · Physics 2009-09-29 Olga Arias , Tame Gonzalez , Israel Quiros

Assuming conformally flat metric we obtain inhomogeneous solutions of Einstein equations with the energy-momentum of a viscous fluid. We suggest that the viscous solution can be applied as a model of an expanding inhomogeneous dark energy.

General Relativity and Quantum Cosmology · Physics 2020-03-31 Z. Haba

We present two classes of inhomogeneous, spherically symmetric solutions of the Einstein-Maxwell-Perfect Fluid field equations with cosmological constant generalizing the Vaidya-Shah solution. Some special limits of our solution reduce to…

General Relativity and Quantum Cosmology · Physics 2019-10-09 Metin Gurses , Yaghoub Heydarzade

The staid subject of exact static spherically symmetric perfect fluid solutions of Einstein's equations has been reinvigorated in the last decade. We now have several solution generating techniques which give rise to new exact solutions.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kayll Lake

This diploma thesis analyses static, spherically symmetric perfect fluid solutions to Einstein's field equations with cosmological constant. Constant density solutions are derived for different values of the cosmological constant. Eleven…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Christian G. Boehmer

A framework is introduced which explains the existence and similarities of most exact solutions of the Einstein equations with a wide range of sources for the class of hypersurface-homogeneous spacetimes which admit a Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Claes Uggla , Robert T. Jantzen , Kjell Rosquist

We investigate an exact solution that describes the embedding of the four-dimensional (4D) perfect fluid in a five-dimensional (5D) Einstein spacetime. The effective metric of the 4D perfect fluid as a hypersurface with induced matter is…

High Energy Physics - Theory · Physics 2008-11-26 Jie Ren , Xin-He Meng , Liu Zhao

A new approach to tackle Einstein equations for an isotropic and homogeneous Friedmann--Robertson--Walker Universe in the presence of a quintessence scalar field is devised. It provides a way to get a simple exact solution to these…

General Relativity and Quantum Cosmology · Physics 2016-04-12 Felipe A. Asenjo , Sergio A. Hojman

We consider static cosmological solutions along with their stability properties in the framework of a recently proposed theory of massive gravity. We show that the modifcation introduced in the cosmological equations leads to several new…

General Relativity and Quantum Cosmology · Physics 2012-07-27 Luca Parisi , Ninfa Radicella , Gaetano Vilasi

Perfect-fluid, static, cylindrically symmetric solutions of Einstein's field equations are obtained for the equations of state $\rho+3p=0$ and $\rho=p$. In the former case, the density and the pressure turn out to be constant while in the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 M. Sharif

We find the general behaviour of homogeneous and isotropic cosmological models in some fourth-order theories of gravity. Explicit, exact, general solutions are given for both empty universes and those filled with a perfect fluid. For the…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Timothy Clifton

We present an exact analytical solution of the Einstein equations with cosmological constant in a spatially flat Robertson-Walker metric. This is interpreted as an isotropic Lemaitre-type version of the cosmological Friedmann model.…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Ion I. Cotaescu , Dumitru N. Vulcanov

In this paper we present a class of exact inhomogeneous solutions to Einstein's equations for higher dimensional Szekeres metric with perfect fluid and a cosmological constant. We also show particular solutions depending on the choices of…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Subenoy Chakraborty , Ujjal Debnath

We investigate the global dynamics of the field equations of (pure) quadratic theories of gravity which generalise Einstein's theory in spatially flat homogeneous and isotropic cosmological models with a perfect fluid. We introduce global…

General Relativity and Quantum Cosmology · Physics 2026-03-11 Artur Alho , Margarida Lima , Filipe C. Mena

In this paper we study cosmological solutions to the Einstein--Euler equations. We first establish the future stability of nonlinear perturbations of a class of homogeneous solutions to the relativistic Euler equations on fixed linearly…

Analysis of PDEs · Mathematics 2024-07-25 David Fajman , Maximilian Ofner , Todd A. Oliynyk , Zoe Wyatt

We present a class of singularity free exact cosmological solutions of Einstein's equations describing a perfect fluid with heat flow. It is obtained as generalization of the Senovilla class [1] corresponding to incoherent radiation field.…

General Relativity and Quantum Cosmology · Physics 2010-04-06 L. K. Patel , Naresh Dadhich

Following a solution generating technique introduced recently by one of us, we transform the Einstein static Universe into a two - fold infinity class of physically acceptable exact perfect fluid solutions of Einstein's equations. Whereas…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Cédric Grenon , Pascal J. Elahi , Kayll Lake

We investigate the interior Einstein's equations in the case of a static, axially symmetric, perfect fluid source. We present a particular line element that is specially suitable for the investigation of this type of interior gravitational…

General Relativity and Quantum Cosmology · Physics 2022-03-29 Medeu Abishev , Farida Belissarova , Kuantay Boshkayev , Hernando Quevedo , Saken Toktarbay , Aizhan Mansurova , Aray Muratkhan

We establish the future non-linear stability of Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) solutions to the Einstein-Euler equations of the universe filled with a large class of perfect fluids (the equations of state are allowed to be…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Chao Liu , Changhua Wei

We have found exact constant solutions for the cosmological density parameter using a generalization of general relativity that incorporates a cosmic time-variation of the velocity of light in vacuum and the Newtonian gravitation constant.…

Astrophysics · Physics 2009-10-31 Luis P. Chimento , Alejandro S. Jakubi