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In this paper, we investigate the evolution of cosmological perturbations within the context of Bianchi Type$-I$ spacetimes. We consider models containing viscous fluids with evolving cosmological (\LL) and Newtonian gravitational (G)…

General Relativity and Quantum Cosmology · Physics 2023-11-08 Alnadhief H. A. Alfedeel , Maye Elmardi , Amare abebe

Some new exact solutions of Einstein's field equations in a spatially homogeneous and anisotropic Bianchi type-V space-time with minimally interaction of perfect fluid and dark energy components have been obtained. To prevail the…

General Physics · Physics 2011-10-06 Anirudh Pradhan , H. Amirhashchi

In the context of brane cosmology, a scenario where our universe is a 3+1-dimensional surface (the ``brane'') embedded in a five-dimensional spacetime (the ``bulk''), we study geometries for which the brane is anisotropic - more…

High Energy Physics - Theory · Physics 2010-02-03 A. Fabbri , D. Langlois , D. A. Steer , R. Zegers

Some Bianchi type IX viscous fluid cosmological models are investigated. To get a solution a supplementary condition between metric potentials is used. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Anirudh Pradhan , Sudhir Kumar Srivastav , Mahesh K. Yadav

We analyze the dynamics of a Bianchi I cosmology in the presence of a viscous fluid, causally regularized according to the Lichnerowicz approach. We show how the effect induced by shear viscosity is still able to produce a matter creation…

General Relativity and Quantum Cosmology · Physics 2017-09-13 Giovanni Montani , Marta Venanzi

Bianchi type III string cosmological models with bulk viscous fluid for massive string are investigated. To get the determinate model of the universe, we have assumed that the coefficient of bulk viscosity ($\xi$) is inversely proportional…

General Relativity and Quantum Cosmology · Physics 2009-03-19 Raj Bali , Anirudh Pradhan

In this article, we consider a newly proposed parameterization of the viscosity coefficient $\zeta$, specifically $\zeta=\bar{\zeta}_0 {\Omega^s_m} H $, where $\bar{\zeta}_0 = \frac{\zeta_0}{{\Omega^s_{m_0}}} $ within the coincident $f(Q)$…

General Relativity and Quantum Cosmology · Physics 2024-01-17 Dheeraj Singh Rana , Raja Solanki , P. K. Sahoo

We obtain a general exact solution of the Einstein field equations for the anisotropic Bianchi type I universes filled with an exponential-potential scalar field and study their dynamics. It is shown, in agreement with previous studies,…

General Relativity and Quantum Cosmology · Physics 2010-11-01 J. M. Aguirregabiria , A. Feinstein , J. Ibanez

With the non-metricity scalar $Q$ as the functional argument, several $f(Q)$ gravity models are found to be proposed which are perfectly able to mimic the late-time accelerated expansion as pointed out by the type Ia supernovae…

General Relativity and Quantum Cosmology · Physics 2026-02-03 Subhajit Pal , Atanu Mukherjee , Ritabrata Biswas , Farook Rahaman

The present paper deals with quantization of perfect fluid anisotropic cosmological models. Bianchi type V and IX models are discussed following Schutz's method of expressing fluid velocities in terms of six potentials. The wave functions…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Barun Majumder , Narayan Banerjee

Anisotropic cloud string cosmological model with Bianchi type I space time is investigated in the context of general relativity. The exact solutions of Einstein field equations are obtained with when the source for energy momentum tensor is…

General Physics · Physics 2019-09-26 Kangujam Priyokumar Singh , Meher Daimary

We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether cyclic universe…

General Relativity and Quantum Cosmology · Physics 2016-05-25 John D. Barrow , Chandrima Ganguly

In this paper, we study the dynamics of a Bianchi Type I potential in the presence of a concave potential of the form $V(\phi) = V_0 \left[1- \left( \frac{\phi}{\mu}\right)^n\right]$, where $V_0$ is a constant, and $\mu$ is a mass scale. We…

General Relativity and Quantum Cosmology · Physics 2017-04-10 Ikjyot Singh Kohli , Michael C. Haslam

A new class of LRS Bianchi type ${\rm VI}_{0}$ cosmological models with free gravitational fields and a variable cosmological term is investigated in presence of perfect fluid as well as bulk viscous fluid. To get the deterministic solution…

General Relativity and Quantum Cosmology · Physics 2012-04-13 Anirudh Pradhan , Shyam Sundar Kumhar , Padmini Yadav , Kanti Jotania

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

A spatially homogeneous and anisotropic Bianchi type V cosmological model of the universe for perfect fluid within the framework of Scale covariant theory of gravitation proposed by Canuto et al., is studied in view of a variable…

General Physics · Physics 2017-04-13 Mohd. Zeyauddin , C. V. Rao

In this work, we investigate the cosmological dynamics of an anisotropic Universe within the framework of $f(R,T)$ gravity by incorporating pressureless dark matter and the dark energy models. The analysis is carried out in a Bianchi type-I…

General Relativity and Quantum Cosmology · Physics 2026-05-13 S. H. Shekh , N. Myrzakulov , Anirudh Pradhan , M. Zeyauddin

In this paper we investigate the past evolution of an anisotropic Bianchi I universe in $R+R^2$ gravity. Using the dynamical system approach we show that there exists a new two-parameters set of solutions that includes both an isotropic…

General Relativity and Quantum Cosmology · Physics 2018-05-09 Daniel Müller , Angelo Ricciardone , Alexei A. Starobinsky , Aleksey Toporensky

A spatially homogeneous Bianchi type VI0 model containing a viscous fluid in the presence of an axial magnetic field has been studied. A barotropic equation of state together with a pair of linear relations among the square root of matter…

General Relativity and Quantum Cosmology · Physics 2021-05-18 Marcelo Byrro Ribeiro , Abhik Kumar Sanyal

We study the late-time evolution of an anisotropic Bianchi-I universe with radiation in the framework of asymptotically safe gravity. We first discuss the radiation-dominated universe for the perfect fluid with the equation of state…

General Relativity and Quantum Cosmology · Physics 2026-04-24 Chiang-Mei Chen , Ting-Kui Fan , Rituparna Mandal , Nobuyoshi Ohta