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In this manuscript, we investigate the oscillatory behaviour of the anisotropy in the diagonal Bianchi-I spacetimes. Our starting point is a simplification of Einstein's equations using only observable or physical variables. As a…

General Relativity and Quantum Cosmology · Physics 2021-04-02 Leandro G Gomes , Bruno B. Bizarria , Gabriel A. de Souza Silva , William O. Clavijo

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

Differential rotation is central to a great many mysteries in stars and planets. In Part I we predicted the order of magnitude and scaling of the differential rotation in both hydrodynamic and magnetohydrodynamic convection zones. Our…

Solar and Stellar Astrophysics · Physics 2020-09-02 Adam S. Jermyn , Shashikumar M. Chitre , Pierre Lesaffre , Christopher A. Tout

We study the cosmological evolution and singularity crossing in the Bianchi-I universe filled with a conformally coupled scalar field and compare them with those of the Bianchi-I universe filled with a minimally coupled scalar field. We…

General Relativity and Quantum Cosmology · Physics 2018-02-07 A. Yu. Kamenshchik , E. O. Pozdeeva , A. A. Starobinsky , A. Tronconi , G. Venturi , S. Yu. Vernov

Bianchi type V string cosmological models in general relativity are investigated. To get the exact solution of Einstein's field equations, we have taken some scale transformations followed by Camci $\it et ~ al$ (2001). It is shown that…

General Relativity and Quantum Cosmology · Physics 2011-06-07 Anil Kumar Yadav , Vineet Kumar Yadav , Lallan Yadav

We consider redshift drift in a general space-time as expressed in terms of physically interpretable multipole series. An important realisation from the derived results is that redshift drift cannot in general be thought of as a direct…

General Relativity and Quantum Cosmology · Physics 2021-02-03 Asta Heinesen

Bianchi cosmologies are ``natural'' anisotropic extensions of the Friedmann universes and they have long been used to investigate the cosmological implications of anisotropy. The latter introduces new ingredients to the standard scenarios,…

General Relativity and Quantum Cosmology · Physics 2024-09-13 Amalia Tzartinoglou , Christos G. Tsagas

It is shown that all contracting, spatially homogeneous, orthogonal Bianchi cosmologies that are sourced by an ultra-stiff fluid with an arbitrary and, in general, varying equation of state asymptote to the spatially flat and isotropic…

High Energy Physics - Theory · Physics 2009-11-11 James E. Lidsey

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

A systematic dynamical system approach is applied to study the cosmology of anisotropic Bianchi I universes in which a vector field is assumed to operate on a disformal frame. This study yields a number of new fixed points, among which…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-02 Tomi S. Koivisto , Federico R. Urban

We present an effective Eulerian description, in the non-relativistic regime, of the growth of cosmological perturbations around a homogeneous but anisotropic Bianchi I spacetime background. We assume a small deviation from isotropy,…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-10 Juan P. Beltrán Almeida , Josué Motoa-Manzano , Jorge Noreña , Thiago S. Pereira , César A. Valenzuela-Toledo

A Bianchi type I string cosmological model in the presence of a magnetic flux is investigated. A few plausible assumptions regarding the parametrization of the cosmic string and magneto-fluid are introduced and some exact analytical…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha , Mihai Visinescu

This manuscript is devoted to investigate Bianchi Type $I$ universe in the context of $f(R,T)$ gravity. For this purpose, we explore the exact solutions of locally rotationally symmetric Bianchi type $I$ spacetime. The modified field…

General Physics · Physics 2015-08-07 M. Farasat Shamir

A new class of a spatially homogeneous and anisotropic Bianchi type-I cosmological models of the universe for perfect fluid distribution within the framework of scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett.…

General Physics · Physics 2012-11-15 Anirudh Pradhan , Ajay Kumar Singh , H. Amirhashchi

The flat anisotropic model of the early Universe is considered. Two interacting scalar fields with special form of potential energy are a source of matter fields. Analytic solutions for inflationary and scalaron stages are found. It is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Vladimir Folomeev

Recent independent observations using several different telescope systems an analysis methods have provided evidence of parity violation between the number of galaxies that spin in opposite directions. On the other hand, other studies…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-08 Lior Shamir

I review the assumptions and observations that motivate the concept of the extragalactic cosmic background radiation, and the issues of energy accounts and star formation history as a function of galaxy morphological type that figure in the…

Astrophysics · Physics 2007-05-23 P. J. E. Peebles

In this paper, we present a model of transitioning universe with minimal interaction between perfect fluid and anisotropic dark energy in Bianchi I space-time. The two sources are assumed to minimally interacted and therefore their energy…

General Relativity and Quantum Cosmology · Physics 2016-08-19 Anil Kumar Yadav

A large fraction of the information collected by cosmological surveys is simply discarded to avoid lengthscales which are difficult to model theoretically. We introduce a new technique which enables the extraction of useful information from…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-08 Fergus Simpson , J. Berian James , Alan F. Heavens , Catherine Heymans

Current cosmological data seem to show that dark energy is evolving in time and that it possibly crossed the phantom divide in the past. So far the only theories that lead to such a behavior involve a non-trivial coupling between dark…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-02 William J. Wolf , Pedro G. Ferreira , Carlos García-García