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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

Homogeneous, nearly-isotropic Bianchi cosmological models are considered. Their time evolution is expressed as a complete set of non-interacting linear modes on top of a Friedmann-Robertson-Walker background model. This connects the…

General Relativity and Quantum Cosmology · Physics 2011-09-08 Andrew Pontzen , Anthony Challinor

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

We study the late time evolution of a class of exact anisotropic cosmological solutions of Einstein's equations, namely spatially homogeneous cosmologies of Bianchi type VII$_0$ with a perfect fluid source. We show that, in contrast to…

General Relativity and Quantum Cosmology · Physics 2009-10-31 J. Wainwright , M. J. Hancock , C. Uggla

We construct a cosmological model which is physically reasonable, mathematically tractable, and extends the study of CDM models to the case where the equations of state (EoS) for matter and dark energy (DE) vary with time. It is based on…

General Relativity and Quantum Cosmology · Physics 2012-06-14 J. Ponce de Leon

Within the scope of Bianchi type-VI cosmological model we study the role of spinor field in the evolution of the Universe. It is found that due to the spinor affine connections the energy-momentum tensor of the spinor field possesses…

General Relativity and Quantum Cosmology · Physics 2016-05-24 Bijan Saha

In this work we present a new scheme to study the tachyon dark energy model using dynamical systems analysis by considering parametrization of the equation of state(EoS) of the dark energy. Both the canonical and phantom field dynamics are…

General Relativity and Quantum Cosmology · Physics 2023-03-21 Saddam Hussain , Saikat Chakraborty , Nandan Roy , Kaushik Bhattacharya

We explore locally rotationally symmetric Bianchi I universe in Brans-Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also…

General Relativity and Quantum Cosmology · Physics 2015-06-05 M. Sharif , Saira Waheed

The purpose of this short review is to describe cosmological models with a linear inhomogeneous time-dependent equation of state (EoS) for the dark energy, when the dark fluid is coupled with dark matter. This may lead to a bounce…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Iver Brevik , Alexander Timoshkin

In this paper, we have analyzed the significance of bulk viscosity in an axially symmetric Bianchi type-I model to study the accelerated expansion of the universe. We have considered four bulk viscosity parameterizations for the…

General Relativity and Quantum Cosmology · Physics 2022-12-21 Archana Dixit , Anirudh Pradhan , Vinod Kumar Bhardwaj , A. Beesham

We have examined the cosmological actions of LRS (Locally Rationally Symmetric) Bianchi type-I universe model in $f(R,T^\psi)$ gravity. For this, we have estimated the Hubble parameter, the effective equation of state parameter…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Mohit Thakre , Praveen Kumar Dhankar , Safiqul Islam , Parbati Sahoo , Farook Rahaman , Behnam Pourhassan

Following recent considerations of a non-zero value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and…

Astrophysics · Physics 2011-04-15 Paulo Aguiar , Paulo Crawford

A generally anisotropic equation of state originally derived in the context of Newman-Janis rotating systems allows for vacuum energy at a specific density. In this paper we examine the possibility of using that equation of state for…

General Relativity and Quantum Cosmology · Physics 2023-09-08 Philip Beltracchi

We investigate the behaviour of the skewness parameters for an anisotropic universe in the framework of General Relativity. Non interacting dark energy is considered in presence of electromagnetic field. A time varying deceleration…

General Physics · Physics 2022-07-19 B. Mishra , Pratik P Ray , S. K. Tripathy , Kazuharu Bamba

A self-consistent system of interacting nonlinear spinor and scalar fields within the scope of a Bianchi type-I cosmological model filled with perfect fluid is considered. Exact self-consistent solutions to the corresponding field equations…

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

Gravitational collapse of a spherically symmetric homogeneous perfect barotropic fluid with linear as well as polytropic type Equation of State (EoS) has been investigated in the framework of a linear model of $f(R,T)$ gravity. This…

General Relativity and Quantum Cosmology · Physics 2020-05-06 Karim Mosani , Gauranga C. Samanta

We investigate diagonal Bianchi-I spacetimes in the presence of viscous fluids by using the shear and the anisotropic pressure components as the basic variables, where the viscosity is driven by the (second-order) causal thermodynamics. A…

General Relativity and Quantum Cosmology · Physics 2017-02-13 Eduardo Bittencourt , Leandro G. Gomes , Renato Klippert

In homogeneous and isotropic loop quantum cosmology, gravity can behave repulsively at Planckian energy densities leading to the replacement of the big bang singularity with a big bounce. Yet in any bouncing scenario it is important to…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Dah-Wei Chiou , Kevin Vandersloot

In this paper we study the evolution of the dark energy parameter within the scope of a spatially homogeneous and isotropic Friedmann-Robertson-Walker (FRW) model filled with barotropic fluid and dark energy by revisiting the recent results…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha , Hassan Amirhashchi , Anirudh Pradhan

It is performed a detailed dynamical analysis for a bulk viscosity model in the full Israel-Stewart formalism for a spatially flat Friedmann-Robertson-Walker Universe. In our study we have considered the total cosmic fluid constituted by…

General Relativity and Quantum Cosmology · Physics 2017-08-02 Samuel Lepe , Giovanni Otalora , Joel Saavedra
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