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We consider the cosmology where some function f(G) of the Gauss-Bonnet term G is added to the gravitational action to account for the late-time accelerating expansion of the universe. The covariant and gauge invariant perturbation equations…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Baojiu Li , John D. Barrow , David F. Mota

A new gauge-invariant approach for describing cosmological perturbations is developed. It is based on a physically motivated splitting of the stress-energy tensor of the perturbation into two parts - the bare perturbation and the…

General Relativity and Quantum Cosmology · Physics 2011-07-19 Sergei M. Kopeikin , Juan Ramirez , Bahram Mashhoon , Mikhail V. Sazhin

The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum cosmology coupled to a massless scalar field. As in the Euclidean case, the discreteness of quantum geometry removes the classical singularity from the quantum…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Franz Hinterleitner , Seth Major

We obtain the general cosmological evolution equations for a classically consistent theory of bimetric gravity. Their analytic solutions are demonstrated to generically allow for a cosmic evolution starting out from a matter dominated FLRW…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Mikael von Strauss , Angnis Schmidt-May , Jonas Enander , Edvard Mortsell , S. F. Hassan

Currently, in order to explain the accelerated expansion phase of the universe, several alternative approaches have been proposed, among which the most common are dark energy models and alternative theories of gravity. Although these…

General Relativity and Quantum Cosmology · Physics 2021-08-24 I. S. Farias , P. H. R. S. Moraes

We show the first simple, systematic and direct approach to decoupling gravitational sources in general relativity. As a direct application, a robust and simple way to generate anisotropic solutions for self-gravitating systems from perfect…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Jorge Ovalle

To find more deliberate f(R,T) cosmological solutions, we proceed our previous paper further by studying some new aspects of the considered models via investigation of some new cosmological parameters/quantities to attain the most…

General Relativity and Quantum Cosmology · Physics 2017-05-23 Hamid Shabani , Mehrdad Farhoudi

In the cosmological scenario in $f\left( T\right) $ gravity, we find analytical solutions for an isotropic and homogeneous universe containing a dust fluid and radiation and for an empty anisotropic Bianchi I universe. The method that we…

General Relativity and Quantum Cosmology · Physics 2016-08-01 Andronikos Paliathanasis , John D. Barrow , P. G. L. Leach

In this paper we show that any static and spherically symmetric anisotropic solution of the Einstein field equations can be thought as a system sourced by certain deformed isotropic system in the context of Minimal Geometric…

General Relativity and Quantum Cosmology · Physics 2018-09-26 Ernesto Contreras

In the present article, we have constructed a static charged anisotropic compact star model of Einstein field equations for a spherically symmetric space-time geometry. Specifically, we have extended the charged isotropic Heintzmann…

General Relativity and Quantum Cosmology · Physics 2018-08-29 E. Morales , Francisco Tello-Ortiz

The recent theoretical advance known as the Minimal Geometric Deformation (MGD) method has initiated a renewed interest in investigating higher curvature gravitational effects in relativistic astrophysics. In this work, we model a strange…

General Relativity and Quantum Cosmology · Physics 2022-02-16 S. K. Maurya , Ksh. Newton Singh , M. Govender , Sudan Hansraj

A theory of gravitation is constructed in which all homogeneous and isotropic solutions are nonsingular, and in which all curvature invariants are bounded. All solutions for which curvature invariants approach their limiting values approach…

General Relativity and Quantum Cosmology · Physics 2009-10-22 R. Brandenberger , V. Mukhanov , A. Sornborger

In our investigation, we pioneer the development of geometrically deformed strange stars within the framework of teleparallel gravity theory through gravitational decoupling via the complete geometric deformation (CGD) technique. The…

General Relativity and Quantum Cosmology · Physics 2025-02-05 Sneha Pradhan , Piyali Bhar , Sanjay Mandal , P. K. Sahoo , Kazuharu Bamba

The present article is devoted to the study of local anisotropies effects on the Durgapal's fourth model in the context of gravitational decoupling via the Minimal Geometric Deformation approach. To do it, the most general equation of state…

General Relativity and Quantum Cosmology · Physics 2020-10-21 Francisco Tello-Ortiz , Ángel Rincón , Piyali Bhar , Y. Gomez-Leyton

We investigate FLRW cosmology in the framework of symmetric teleparallel $f(Q)$ gravity with a nonminimal coupling between dark matter and the gravitational field. In the noncoincidence gauge, the field equations admit an equivalent…

General Relativity and Quantum Cosmology · Physics 2026-03-26 A. Abebe , P. S. Apostolopoulos , A. Giacomini , G. Leon , F. Moncada , A. Paliathanasis

The $f(R,T)$ gravity is an extended theory of gravity in which the gravitational action contains general terms of both the Ricci scalar $R$ and trace of the energy-momentum tensor $T$. In this way, $f(R,T)$ models are capable of describing…

General Relativity and Quantum Cosmology · Physics 2017-07-20 P. H. R. S. Moraes , P. K. Sahoo

We review the status of $f(R,T)$ cosmological models, where $T$ is the trace of the energy momentum tensor $T^{\mu\nu}$. We start focusing on the modified Friedmann equations for the minimally coupled gravitational Lagrangian of the type…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-08 Ana Paula Jeakel , Jonas Pinheiro da Silva , Hermano Velten

This paper investigates some particular anisotropic star models in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ gravity, where $\mathcal{Q}=\mathcal{R}_{\omega\alpha}\mathcal{T}^{\omega\alpha}$. We adopt a standard model…

General Relativity and Quantum Cosmology · Physics 2023-04-05 M. Sharif , T. Naseer

In this work we construct an ultracompact star configuration in the framework of Gravitational Decoupling by the Minimal Geometric Deformation approach. We use the complexity factor as a complementary condition to close the system of…

General Relativity and Quantum Cosmology · Physics 2021-09-15 M. Carrasco-Hidalgo , E. Contreras

Using our anholonomic frame deformation method, we show how generic off-diagonal cosmological solutions depending, in general, on all spacetime coordinates and undergoing a phase of ultra-slow contraction can be constructed in massive…

High Energy Physics - Theory · Physics 2017-06-05 Sergiu I. Vacaru
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