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We show that massless solutions to the Einstein-Vlasov system in a Bianchi I space-time with small anisotropy, i.e. small shear and small trace-free part of the spatial energy momentum tensor, tend to a radiation fluid in an Einstein-de…

General Relativity and Quantum Cosmology · Physics 2024-06-18 Ho Lee , Ernesto Nungesser , Paul Tod

In one-loop string effective action, we study a generality of non-singular cosmological solutions found in the isotropic and homogeneous case. We discuss Bianchi I and IX type spacetimes. We find that nonsingular solutions still exist in…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Hiroki Yajima , Kei-ichi Maeda , Hidetoshi Ohkubo

The approach of a quantum state to a cosmological singularity is studied through the evolution of its moments in a simple version of a Bianchi I model. In spite of the simplicity, the model exhibits several instructive and unexpected…

General Relativity and Quantum Cosmology · Physics 2020-06-03 Ana Alonso-Serrano , Martin Bojowald , David Brizuela

In this paper, we consider spatially homogenous and anisotropic Bianchi type I universe in the context of F(T) gravity. We construct some corresponding models using conservation equation and equation of state parameter representing…

General Relativity and Quantum Cosmology · Physics 2015-05-28 M. Sharif , Shamaila Rani

The general form of the anisotropy parameter of the expansion for Bianchi type-III metric is obtained in the presence of a single diagonal imperfect fluid with a dynamically anisotropic equation of state parameter and a dynamical energy…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Ozgur Akarsu , Can B. Kilinc

We study Bianchi cosmologies in the ghost-free bigravity theory assuming both metrics to be homogeneous and anisotropic, of the Bianchi class A, which includes types I,II,VI$_0$,VII$_0$,VIII, and IX. We assume the universe to contain a…

High Energy Physics - Theory · Physics 2013-11-08 Kei-ichi Maeda , Mikhail S. Volkov

Bianchi type $VI_{0}$ massive string cosmological models using the technique given by Letelier (1983) with magnetic field are investigated. To get the deterministic models, we assume that the expansion ($\theta$) in the model is…

General Relativity and Quantum Cosmology · Physics 2015-06-30 Anirudh Pradhan , Raj Bali

We study anisotropic Bianchi-I cosmology, incorporating quantum gravitational corrections into the Einstein equation through the scale-dependent Newton coupling and cosmological term, as determined by the flow equation of the effective…

General Relativity and Quantum Cosmology · Physics 2025-12-03 Chiang-Mei Chen , Akihiro Ishibashi , Rituparna Mandal , Nobuyoshi Ohta

In this article, we propose an anisotropic Bianchi-I type cosmological model in non-conservative Unimodular Gravity ($\mathrm{NUG}$). We show that simply using the Bianchi-I type metric does not resolve a striking characteristic of the…

General Relativity and Quantum Cosmology · Physics 2025-11-26 Marcelo H. Alvarenga , Júlio C. Fabris

We present the classical solutions to the Einstein field equations derived using the WKB-like and Hamilton procedures. The investigation is carried out in the commutative and noncommutative scenario for the Bianchi type I cosmological model…

General Relativity and Quantum Cosmology · Physics 2009-11-13 C. Ortiz , E. Mena-Barboza , M. Sabido , J. Socorro

In this paper, we search the existence of invariant solutions of Bianchi type I space-time in the context of $f\left(R,T\right)$ gravity. The exact solution of the Einstein's field equations are derived by using Lie point symmetry analysis…

General Physics · Physics 2018-02-01 Anil Kumar Yadav , Ahmad T. Ali

We study a homogeneous and nearly-isotropic Universe permeated by a homogeneous magnetic field. Together with an isotropic fluid, the homogeneous magnetic field, which is the primary source of anisotropy, leads to a plane-symmetric Bianchi…

Cosmology and Nongalactic Astrophysics · Physics 2012-01-11 Julian Adamek , Ruth Durrer , Elisa Fenu , Marc Vonlanthen

We investigate the cosmological solutions in closed bosonic string theory in the presence of non zero tachyon condensate. We specifically obtain time dependent solutions which describe an anisotropic universe. We also discuss the nature of…

High Energy Physics - Theory · Physics 2009-10-28 Swapna Mahapatra , Sudipta Mukherji

A spatially homogeneous and anisotropic Bianchi Type I universe has been studied with {\omega} <-1 without Big Smash. It is demonstrated that if cosmic dark energy behaves like a fluid with equation of state p = {\omega}{\rho} (p and {\rho}…

General Relativity and Quantum Cosmology · Physics 2011-08-04 Anil Kumar Yadav

The paper presents some exact solutions of Bianchi types I, III and Kantowski-Sachs cosmological models consisting of a dissipative fluid along with an axial magnetic field. A barytropic equation of state between the thermodynamic pressure…

General Relativity and Quantum Cosmology · Physics 2021-05-18 A. Banerjee , Abhik Kumar Sanyal

This paper is devoted to study Bianchi type I cosmological model in Brans-Dicke theory with self-interacting potential by using perfect, anisotropic and magnetized anisotropic fluids. We assume that the expansion scalar is proportional to…

General Relativity and Quantum Cosmology · Physics 2015-06-04 M. Sharif , Saira Waheed

We study nature of singularities in anisotropic string-inspired cosmological models in the presence of a Gauss-Bonnet term. We analyze two string gravity models-- dilaton-driven and modulus-driven cases-- in the Bianchi type-I background…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Alexey Toporensky , Shinji Tsujikawa

Locally rotationally symmetric (LRS) Bianchi Type I cosmological models are examined in the presence of dynamically anisotropic dark energy and perfect fluid. We assume that the dark energy (DE) is minimally interacting, has dynamical…

General Relativity and Quantum Cosmology · Physics 2014-11-18 Ozgur Akarsu , Can B. Kilinc

We discuss a spatially homogeneous and anisotropic Bianchi type-I space-time with two fluids as the content of the Universe: matter and holographic dark energy in the framework of general relativity. To get the exact solutions of Einstein's…

General Relativity and Quantum Cosmology · Physics 2023-02-03 M. Koussour , M. Bennai

Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VI_h string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Dominic Clancy , Alexander Feinstein , James E. Lidsey , Reza Tavakol
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