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Related papers: Some Inhomogeneous Magnetized Viscous Fluid Cosmol…

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We consider inhomogeneous viscous fluids in flat Friedmann-Robertson-Walker universe. We analyze different kinds of such fluids and investigate the possibility to reproduce the current cosmic acceleration providing a different future…

General Relativity and Quantum Cosmology · Physics 2015-09-21 Shynaray Myrzakul , Ratbay Myrzakulov , Lorenzo Sebastiani

The holographic principle in a radiation dominated universe, as discussed first by Verlinde (2000), is extended so as to incorporate the case of a bulk-viscous cosmic fluid. This corresponds to a non-conformally invariant theory.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Iver Brevik

Within the context of a cosmic space whose energy source is modeled with a perfect fluid, a uniform model of Universe based on a standard FRW cosmology containing decoupled mixed matter sources namely stiff matter and cosmic dust together…

General Relativity and Quantum Cosmology · Physics 2016-09-07 Denisa-Andreea Mihu

A new type of fluid matter model in general relativity is introduced, in which the fluid particles are subject to velocity diffusion without friction. In order to compensate for the energy gained by the fluid particles due to diffusion, a…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Simone Calogero

The statefinder diagnostic pair is adopted to differentiate viscous cosmology models and it is found that the trajectories of these viscous cosmology models on the statefinder pair $s-r$ plane are quite different from those of the…

Astrophysics · Physics 2009-11-13 M. Hu , Xin He Meng

In this paper, we have derived the field equations in an extended theory of gravity in an anisotropic space time background and in the presence of magnetic field. The physical and geometrical parameters of the models are determined with…

General Relativity and Quantum Cosmology · Physics 2022-07-19 Sankarsan Tarai , Fakhereh Md. Esmaeili , B. Mishra , S. K. Tripathy

We consider the influence of the perturbative bulk viscosity on the evolution of the Hubble parameter in the QCD era of the early Universe. For the geometry of the Universe we assume the homogeneous and isotropic…

General Relativity and Quantum Cosmology · Physics 2010-11-24 A. Tawfik , M. Wahba , H. Mansour , T. Harko

We investigate the cosmological perturbation dynamics for a universe consisting of pressureless baryonic matter and a viscous fluid, the latter representing a unified model of the dark sector. In the homogeneous and isotropic background the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-21 W. S. Hipólito-Ricaldi , H. E. S. Velten , W. Zimdahl

Running vacuum models and viscous dark matter scenarios beyond perfect fluid idealization are two appealing theoretical strategies that have been separately studied as alternatives to solve some problems rooted in the $\Lambda$CDM…

General Relativity and Quantum Cosmology · Physics 2023-04-26 Norman Cruz , Gabriel Gomez , Esteban Gonzalez , Guillermo Palma , Angel Rincon

The study of a self-consistent system of nonlinear spinor and Bianchi type I gravitational fields in presence of a viscous fluid and $\Lambda$ term with the spinor field nonlinearity being some arbitrary functions of the invariants $I$ an…

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

We study the flow of an electrically charged fluid through an elastic and porous medium. A three continuum model consisting of an elastic solid, a viscous fluid, and a mobile charge continuum is used. The relevant laws of physics are…

Soft Condensed Matter · Physics 2024-03-19 Jiashi Yang

In this article we have presented FRW cosmological model in the framework of Brans-Dicke theory. This paper deals with a new proposed form of deceleration parameter and cosmological constant. The effect of bulk viscosity is also studied in…

General Relativity and Quantum Cosmology · Physics 2017-07-27 G. P. Singh , Binaya K. Bishi

We find a class of cylindrically symmetric, static electrovacuum spacetimes generated by a non-homogeneous magnetic field and involving the cosmological constant and one additional parameter, which determine uniquely the strength of the…

General Relativity and Quantum Cosmology · Physics 2021-04-07 Jiří Veselý , Martin Žofka

We study a uniform and isotropic cosmology with a decaying vacuum energy density, in the realm of a model with a time varying gravitational "constant". We show that, for late times, such a cosmology is in accordance with the observed values…

General Relativity and Quantum Cosmology · Physics 2016-11-09 Saulo Carneiro

A cosmological model with an inhomogeneous viscous dark fluid coupled with dark matter in a flat Friedman-Robertson-Walker universe is investigated. The influence of dark matter on the behavior of an inhomogeneous viscous fluid of this…

General Relativity and Quantum Cosmology · Physics 2015-06-22 E. Elizalde , V. V. Obukhov , A. V. Timoshkin

Cylindrically symmetric inhomogeneous string cosmological models in presence of electromagnetic field is investigated. We have assumed that $F_{12}$ is the only non-vanishing component of $F_{ij}$. The Maxwell's equations require that…

General Relativity and Quantum Cosmology · Physics 2014-05-06 Anirudh Pradhan , Anju Rai , Raj Bali

In this paper we construct modified cosmic Chaplygin gas which has viscosity. We use exponential function method to solve non-linear equation and obtain time-dependent dark energy density. Then discuss Hubble expansion parameter and scale…

General Relativity and Quantum Cosmology · Physics 2013-06-05 Behnam Pourhassan

A universe consisting of two interacting perfect fluids with the same 4-velocity is considered. A heuristic mean free time argument is used to show that the system as a whole cannot be perfect as well but neccessarily implies a nonvanishing…

Astrophysics · Physics 2015-06-24 Winfried Zimdahl

Bulk viscosity is the only viscous influence that can change the background dynamics in a homogeneous and isotropic universe. In the present work, we analyze the bulk viscous cosmological model with the bulk viscosity coefficient of the…

General Relativity and Quantum Cosmology · Physics 2021-12-13 Gaurav Gadbail , Simran Arora , P. K. Sahoo

The authors considered the bulk viscous fluid in $f(R, T)$ gravity within the framework of Kaluza-Klein space time. The bulk viscous coefficient $(\xi)$ expressed as $\xi=\xi_0+\xi_1\frac{\dot{a}}{a}+\xi_2\frac{\ddot{a}}{\dot{a}}$, where…

General Relativity and Quantum Cosmology · Physics 2017-04-26 G. C. Samanta , R. Myrzakulov , Parth Shah