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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

Cosmological solutions of Einstein's equations for equilibrium statistical systems of particles with scalar interaction are investigated. It is shown that the scalar field can effectively change the state equation of a statistical system,…

General Relativity and Quantum Cosmology · Physics 2010-11-29 Yu. G. Ignatyev , R. F. Miftakhov

A cosmological model is proposed for the current Universe consisted of non-interacting baryonic matter and interacting dark components. The dark energy and dark matter are coupled through their effective barotropic indexes, which are…

Astrophysics · Physics 2009-06-15 Luis P. Chimento , Monica Forte , Gilberto M. Kremer

In this paper I investigate the possibility to test Einstein's equations with observations of cosmological large scale structure. I first show that we have not tested the equations in observations concerning only the homogeneous and…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-31 Ruth Durrer

We study Einstein's equations with an isotropic but inhomogeneous metric in the cosmic rest frame. The equations are solved perturbatively in the late Universe. The leading plus next-to-leading order results agree with observations without…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-23 Günter Scharf

The quest to understand better the nature of the initial cosmological singularity is with us since the discovery of the expanding universe. Here, we propose several non-flat models, among them the standard cosmological scenario with a…

General Relativity and Quantum Cosmology · Physics 2021-12-28 Andres Felipe Estupinan Salamanca , Sergio Bravo Medina , Marek Nowakowski , Davide Batic

The complete theory of cosmological evolution's macroscopic description is constructed with a help of self-consistent field. The theory includes a subsystem of linear equations of perturbations' evolution and nonlinear macroscopic Einstein…

General Relativity and Quantum Cosmology · Physics 2020-07-09 Yu. G. Ignat'ev

The Einstein equations with a positive cosmological constant are coupled to the pressureless perfect fluid matter in plane symmetry. Under suitable restrictions on the initial data, the resulting Einstein-dust system is proved to have a…

General Relativity and Quantum Cosmology · Physics 2007-09-26 S. B. Tchapnda

Using squeezed vacuum state formalism of quantum optics, an approximate solution to the semiclassical Einstein equation is obtained in Bianchi type-I universe. The phenomena of nonclassical particle creation is also examined in the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 P. K. Suresh

We develop a new approach to building cosmological models, in which small pieces of perturbed Minkowski space are joined together at reflection-symmetric boundaries in order to form a global, dynamical space-time. Each piece of this…

General Relativity and Quantum Cosmology · Physics 2016-04-12 Viraj A. A. Sanghai , Timothy Clifton

Einstein-Vlasov system is solved for a homogeneous isotropic spacetime with positive curvature. In the case of the Universe consisting of massless particles the equation for R(t) is solved analytically.

General Relativity and Quantum Cosmology · Physics 2008-02-03 Tigran Aivazian

We consider the conformal Einstein equations for massless collisionless gas cosmologies which admit an isotropic singularity. It is shown that the Cauchy problem for these equations is well-posed with data consisting of the limiting…

General Relativity and Quantum Cosmology · Physics 2011-07-19 K. Anguige

An introduction to solutions of the Einstein equations defining cosmological models with accelerated expansion is given. Connections between mathematical and physical issues are explored. Theorems which have been proved for solutions with…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Alan D. Rendall

We use a dynamical systems analysis to investigate the future behaviour of Einstein-Aether cosmological models with a scalar field coupling to the expansion of the aether and a non-interacting perfect fluid. The stability of the equilibrium…

General Relativity and Quantum Cosmology · Physics 2013-03-14 Patrik Sandin , Bassemah Alhulaimi , Alan Coley

We perform large-scale cosmological simulations that solve Einstein's equations directly via numerical relativity. Starting with initial conditions sampled from the cosmic microwave background, we track the emergence of a cosmic web without…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-27 Hayley J. Macpherson , Daniel J. Price , Paul D. Lasky

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

We construct exact static inhomogeneous solutions to Einstein's equations with counter flow of particle fluid and a positive cosmological constant by using the Sasaki metrics on three-dimensional spaces. The solutions, which admit an…

High Energy Physics - Theory · Physics 2022-03-23 Hideki Ishihara , Satsuki Matsuno

For a universe containing cosmological constant together with uniform arrangements of magnetic fields, strings, or domain walls, exact solutions to the Einstein equations are shown to lead to a universe with ellipsoidal expansion. The…

High Energy Physics - Phenomenology · Physics 2009-11-10 Arjun Berera , Roman V. Buniy , Thomas W. Kephart

A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein's field equations, known as Bianchi cosmologies, only a subset…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-23 Daniela Saadeh , Stephen M. Feeney , Andrew Pontzen , Hiranya V. Peiris , Jason D. McEwen

On the basis of the relativistic kinetic theory the relativistic statistical systems with scalar interaction particles are investigated. The self-consistent system of the equations describing self-gravitating plasma with interpartial scalar…

General Relativity and Quantum Cosmology · Physics 2013-07-10 Yu. G. Ignat'ev