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The dynamics of cosmological models with isotropic matter sources (perfect fluids) is extensively studied in the literature; in comparison, the dynamics of cosmological models with anisotropic matter sources is not. In this paper we…

General Relativity and Quantum Cosmology · Physics 2011-02-16 Simone Calogero , J. Mark Heinzle

Motivated by the increasing evidence for the need of a geometry that resembles Bianchi morphology to explain the observed anisotropy in the WMAP data, we have discussed some features of the Bianchi type-$VI_{0}$ universes in the presence of…

General Physics · Physics 2015-06-11 Anirudh Pradhan

We present here a phenomenological cosmological model under perfect fluid distribution with a stiff equation of state $p=\rho$. The erstwhile cosmological constant is assumed to be a time dependent variable, i.e., $\Lambda = \Lambda(t)$ in…

Astrophysics · Physics 2008-11-26 Saibal Ray , Utpal Mukhopadhyay

Cosmological solutions are obtained in an anisotropic Kantowski-Sachs (KS) and Bianchi Type-I universes considering a cosmological constant with Skyrme fluid. Interestingly, the solutions obtained here in both the KS and Bianchi-I…

General Relativity and Quantum Cosmology · Physics 2022-06-09 Rikpratik Sengupta , B C Paul , Prasenjit Pal

A Bianchi type-I cosmological model in the presence of a magnetic flux along a cosmological string is investigated. The objective of this study is to generate solutions to the Einstein equations using a few tractable assumptions usually…

General Relativity and Quantum Cosmology · Physics 2015-05-13 Bijan Saha , Victor Rikhvitsky , Mihai Visinescu

In this paper we investigate an observable universe in Bianchi type V space-time by taking into account the cosmological constant as the source of energy. We have performed a $\chi^{2}$ test to obtain the best fit values of the model…

General Physics · Physics 2021-03-23 Rajendra Prasad , Manvinder Singh , Anil Kumar Yadav , A. Beesham

In the present work we have searched the existence of the late time acceleration of the Universe. The matter source that is responsible for the late time acceleration of the Universe consists of cosmic fluid with the equation of state…

General Physics · Physics 2013-01-29 Anil Kumar Yadav , Farook Rahaman , Saibal Ray , G. K. Goswami

Anisotropies generically dominate the earliest stages of expansion of a homogeneous universe. They are particularly relevant in bouncing models, since shears grow in the contracting phase of the cosmos, making the isotropic situation…

General Relativity and Quantum Cosmology · Physics 2020-09-04 Ivan Agullo , Javier Olmedo , V. Sreenath

In a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker universe, we investigate a unified cosmic fluid scenario endowed with bulk viscosity in which the coefficient of the bulk viscosity has a power law evolution. The power law in the…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-20 Weiqiang Yang , Supriya Pan , Eleonora Di Valentino , Andronikos Paliathanasis , Jianbo Lu

Bianchi type I massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel, is investigated. To get the deterministic model of the universe, it is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Raj Bali , Umesh Kumar Pareek , Anirudh Pradhan

We scrutinized the Locally Rotational Symmetry (LRS) Bianchi type-I cosmological model in the presence of fractional holographic dark energy. We calculate the value of the Hubble parameter $H(z)$ using the field equations. After that, we…

General Relativity and Quantum Cosmology · Physics 2025-06-23 Shivangi Rathore , Elangbam Chingkheinganba Meetei , S. Surendra Singh

Conformally flat tilted Bianchi type V cosmological models in presence of a bulk viscous fluid and heat flow are investigated. The coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical and geometric…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Anirudh Pradhan , Abha Rai

We investigate the late-time cosmic acceleration within the framework of viscous $f(T,L_m)$ gravity, where the gravitational action depends on both the torsion scalar $T$ and the matter Lagrangian $L_m$. In this context, the Universe is…

General Physics · Physics 2026-03-24 M. Koussour , Alnadhief H. A. Alfedeel , S. Muminov , J. Rayimbaev

Self-consistent solutions to nonlinear spinor field equations in General Relativity are studied for the case of Bianchi type-I space-time. It has been shown that introduction of $\Lambda$-term in the Lagrangian generates oscillations of the…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha , G. N. Shikin

We build a minimal extension of General Relativity in which Newton's gravitational coupling, $G$, the speed of light, $c$, and the cosmological constant, $\Lambda$, are spacetime variables. This is done while satisfying the contracted…

General Relativity and Quantum Cosmology · Physics 2017-04-27 Guilherme Franzmann

We use one of the simplest forms of the K-essence theory and we apply it to the classical anisotropic Bianchi type I cosmological model, with a barotropic perfect fluid modeling the usual matter content and with cosmological constant. The…

General Relativity and Quantum Cosmology · Physics 2014-09-11 J. Socorro , Luis O. Pimentel , Abraham Espinoza-García

The "improved dynamics" of loop quantum cosmology is extended to include anisotropies of the Bianchi I model. As in the isotropic case, a massless scalar field serves as a relational time parameter. However, the extension is non-trivial…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Abhay Ashtekar , Edward Wilson-Ewing

Inhomogeneous Bianchi type-I cosmological model with electro-magnetic field based on Lyra geometry is investigated. Using separated method, the Einstein field equations have been solved analytically with the aid of Mathematica programm. A…

General Relativity and Quantum Cosmology · Physics 2013-12-12 Ahmad T Ali , F Rahaman

We give the equations governing the shear evolution in Bianchi spacetimes for general f(R)-theories of gravity. We consider the case of R^n-gravity and perform a detailed analysis of the dynamics in Bianchi I cosmologies which exhibit local…

General Relativity and Quantum Cosmology · Physics 2010-11-05 Jannie A Leach , Sante Carloni , Peter K S Dunsby

We study evolution of a flat Friedmann-Robertson Walker universe filled with a bulk viscous cosmological fluid in a higher derivative theory of gravity in the presence of time varying gravitational and cosmological constant. Cosmological…

General Relativity and Quantum Cosmology · Physics 2015-03-13 B. C. Paul , P. S. Debnath
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