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We investigate (4+1)- and (5+0)-dimensional gravity coupled to a non-compact scalar field sigma-model and a perfect fluid within the context of the Randall-Sundrum scenario. We find cosmological solutions with a rolling fifth radius and a…

High Energy Physics - Theory · Physics 2009-10-31 Conall Kennedy , Emil M. Prodanov

We present a general solution of the coupled Einstein-Maxwell field equations (without the source charges and currents) in three spacetime dimensions. We also admit any value of the cosmological constant. The whole family of such…

General Relativity and Quantum Cosmology · Physics 2022-08-23 Jiri Podolsky , Matus Papajcik

Present paper provides a model of static charged anisotropic fluid sphere in the EinsteinMaxwell- GaussBonnet (EMGB) theory of gravitation. We select KB anstz as the metric co-efficient along with electric field intensity. To develop our…

General Physics · Physics 2021-04-13 Piyali Bhar , Megan Govender

We numerically investigate the solutions to the effective equations of the Bianchi II model within the "improved" Loop Quantum Cosmology (LQC) dynamics. The matter source is a massless scalar field. We perform a systematic study of the…

General Relativity and Quantum Cosmology · Physics 2012-10-08 Alejandro Corichi , Edison Montoya

We introduce a new logotropic model based on a complex scalar field with a logarithmic potential that unifies dark matter and dark energy. The scalar field satisfies a nonlinear wave equation generalizing the Klein-Gordon equation in the…

General Relativity and Quantum Cosmology · Physics 2022-10-05 Pierre-Henri Chavanis

We study a perfect fluid Bianchi II models with time varying constants under the self-similarity approach. In the first of the studied model, we consider that only vary $G$ and $\Lambda.$ The obtained solution is more general that the…

General Relativity and Quantum Cosmology · Physics 2009-08-11 José Antonio Belinchón

In the present paper we discuss dynamic of anisotropic Bianchi I Universe filled by the perfect fluid in teleparallel $f(T)$-gravity. By using as analytical as numerical approaches we confirm the main results of previous authors such as…

General Relativity and Quantum Cosmology · Physics 2022-04-25 Petr V. Tretyakov

In this paper, we have found a class of dynamical charged 'black-hole' solutions to Einstein-Maxwell system with a non-zero cosmological constant in a large number of spacetime dimensions. We have solved up to the first sub-leading order…

High Energy Physics - Theory · Physics 2018-12-14 Suman Kundu , Poulami Nandi

We investigate the AdS/CFT interpretation of the class of algebraically special solutions of Einstein gravity with a negative cosmological constant. Such solutions describe a CFT living in a 2+1 dimensional time-dependent geometry that,…

High Energy Physics - Theory · Physics 2014-04-03 Gabriel Bernardi de Freitas , Harvey S. Reall

We show that the Bianchi I Einstein field equations in a perfect fluid scalar field cosmology are equivalent to a linear Schrodinger equation. This is achieved through a special case of the recent FLRW Schrodinger-type formulation, and…

High Energy Physics - Theory · Physics 2007-11-27 Jennie D'Ambroise

We use the expansion-normalized variables approach to study the dynamics of a non-tilted Bianchi Type I cosmological model with both a homogeneous magnetic field and a viscous fluid. In our model the perfect magnetohydrodynamic…

General Relativity and Quantum Cosmology · Physics 2014-02-26 Ikjyot Singh Kohli , Michael C. Haslam

Einstein's field equations for stationary Bianchi type II models with a perfect fluid source are investigated. The field equations are rewritten as a system of autonomous first order differential equations. Dimensionless variables are…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Ulf S. Nilsson , C. Uggla

We study cosmological implications of bigravity and massive gravity solutions with non-simultaneously diagonal metrics by considering the generalized Gordon and Kerr-Schild ansatzes. The scenario that we obtain is equivalent to that of…

General Relativity and Quantum Cosmology · Physics 2016-12-21 Carlos García-García , Antonio L. Maroto , Prado Martín-Moruno

We present a topologically trivial, non-vacuum solution of the Einstein's field equations in four-dimensions, which is regular everywhere. The metric admits circular closed timelike curves, which appear beyond the null curve, and these…

General Relativity and Quantum Cosmology · Physics 2017-12-06 Faizuddin Ahmed

We make use of a flat, axisymmetric Bianchi I metric to investigate the effects of a magnetic field upon the dynamics of the universe for the case in which the accompanying fluid is a cosmological constant and derive two exact solutions to…

Astrophysics · Physics 2008-11-26 Emma J. King , Peter Coles

In cosmological group field theory (GFT) models for quantum gravity coupled to a massless scalar field the total volume, seen as a function of the scalar field, follows the classical Friedmann dynamics of a flat…

General Relativity and Quantum Cosmology · Physics 2023-04-25 Andrea Calcinari , Steffen Gielen

We consider the application of group invariant transformations in order to constrain a flat isotropic and homogeneous cosmological model, containing of a Brans-Dicke scalar field and a perfect fluid with a constant equation of state…

General Relativity and Quantum Cosmology · Physics 2016-03-02 Andronikos Paliathanasis , Michael Tsamparlis , Spyros Basilakos , John D. Barrow

We consider the dynamics of a Bianchi type I spacetime in the presence of dilaton and magnetic fields. The general solution of the Einstein-Maxwell dilaton field equations can be obtained in an exact parametric form. Depending on the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 T. Harko , M. K. Mak

We investigate anisotropic and homogeneous cosmological models in the scalar-tensor theory of gravity with non-minimal kinetic coupling of a scalar field to the curvature given by the function $\eta\cdot(\phi/2)\cdot G_{\mu\nu}\,\nabla^\mu…

General Relativity and Quantum Cosmology · Physics 2025-05-13 Ruslan K. Muharlyamov , Tatiana N. Pankratyeva , Shehabaldeen O. A. Bashir

We propose a new model of cosmology based on an anisotropic background and a specific $f(R)$ theory of gravity. It is shown that field equations of $f(R)$ gravity in a Bianchi type I background give rise to a modified Friedmann equation.…

General Relativity and Quantum Cosmology · Physics 2024-03-21 Cemsinan Deliduman , Oguzhan Kasikci , Vildan Keles Tugyanoglu