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Modern cosmology suggests that the Universe contains two dark components -- dark matter and dark energy -- both unkown in laboratory physics and both lacking direct evidence. Alternatively, a unified dark sector, described by a single…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-21 Hermano Velten , Dominik J. Schwarz

We explore the viability of a bulk viscous matter-dominated Universe to explain the present accelerated expansion of the Universe. The model is composed by a pressureless fluid with bulk viscosity of the form \zeta = \zeta_0 + \zeta_1 * H…

General Relativity and Quantum Cosmology · Physics 2010-10-25 Arturo Avelino , Ulises Nucamendi

We consider the dynamics of a viscous cosmological fluid in the generalized Randall-Sundrum model for an isotropic brane. To describe the dissipative effects we use the Israel-Hiscock-Stewart full causal thermodynamic theory. In the…

High Energy Physics - Theory · Physics 2008-11-26 Chiang-Mei Chen , T. Harko , M. K. Mak

In this paper we have considered a flat FLRW universe with bulk viscous Zel'dovich as the cosmic component. Being considered the bulk viscosity as per the Eckart formalism, we have analyzed the evolution of the Hubble parameter and…

General Relativity and Quantum Cosmology · Physics 2015-08-21 Rajagopalan Nair K. , Titus K. Mathew

We explore the cosmological implications at effective level of matter creation effects in a dissipative fluid for a FLRW geometry; we also perform a statistical analysis for this kind of model. By considering an inhomogeneous Ansatz for the…

General Relativity and Quantum Cosmology · Physics 2021-01-01 Víctor H. Cárdenas , Miguel Cruz , Samuel Lepe

We study the late-time cosmological dynamics of a spatially flat FLRW universe in the framework of $f(Q)$ gravity, where $Q$ denotes the nonmetricity scalar. The matter sector is modeled as a bulk viscous fluid with a free equation-of-state…

General Relativity and Quantum Cosmology · Physics 2026-02-20 Simran Arora , Sai Swagat Mishra , P. K. Sahoo

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

The purpose of the present work is two folded: (1) we propose a new mechanism for the origin of bulk viscosity in cosmological context, and then, (2) we address the thermodynamic implications of viscous cosmology based on the thermodynamics…

General Relativity and Quantum Cosmology · Physics 2025-04-02 Tanmoy Paul

In this paper it has been shown that the neutrino bulk viscous stresses can give rise to the late time acceleration of the universe. It is found that a number of spatially flat FRW models with a negative deceleration parameter can be…

General Relativity and Quantum Cosmology · Physics 2015-05-13 Sudipta Das , Narayan Banerjee

In this article, the bulk viscosity is introduced in a modified gravity model. The gravitational action has a general $f(R,T)$ form, where $R$ and $ T $ are the curvature scalar and the trace of energy momentum tensor respectively. An…

General Relativity and Quantum Cosmology · Physics 2020-10-02 Simran Arora , Xin-he Meng , S. K. J. Pacif , P. K. Sahoo

We consider late-time cosmology in a (phantom) scalar-tensor theory with an exponential potential, as a dark energy model with equation of state parameter close to -1 (a bit above or below this value). Scalar (and also other kinds of)…

High Energy Physics - Theory · Physics 2009-09-17 Emilio Elizalde , Shin'ichi Nojiri , Sergei D. Odintsov

VAMP (variable-mass particles) scenarios, in which the mass of the cold dark matter particles is a function of the scalar field responsible for the present acceleration of the Universe, have been proposed as a solution to the cosmic…

Astrophysics · Physics 2009-11-10 Urbano Franca , Rogerio Rosenfeld

In this work, we have studied, for the first time, the impact of a realistic picture of a time dependent electric and magnetic field on the shear and bulk viscosities of the medium. Both the electric and magnetic fields are considered to be…

High Energy Physics - Phenomenology · Physics 2025-05-15 Debarshi Dey , Gowthama K K , Sadhana Dash , Basanta Kumar Nandi

We discuss bulk viscous cosmological models. Since the bulk viscous pressure is negative, viable viscous cosmological scenarios with late time accelerated expansion can in principle be constructed. After discussing some alternative models…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-20 Hermano Velten

A generic feature of viable $F(R)$ gravity is investigated: It is demonstrated that during the matter dominated era the large frequency oscillations of the effective dark energy may influence the behavior of higher derivatives of the Hubble…

General Relativity and Quantum Cosmology · Physics 2012-12-14 Kazuharu Bamba , Antonio Lopez-Revelles , R. Myrzakulov , S. D. Odintsov , L. Sebastiani

In this work we explore the thermodynamic aspects of dark energy for late future time universe in two different scenarios: as a perfect fluid with constant and variable equation of state parameter; and as dissipative fluid described by a…

General Relativity and Quantum Cosmology · Physics 2022-03-03 David Tamayo

We analyze the dynamical behavior of a quasi-isotropic Universe in the presence of a cosmological fluid endowed with bulk viscosity. We express the viscosity coefficient as a power-law of the fluid energy density:…

General Relativity and Quantum Cosmology · Physics 2009-03-24 Nakia Carlevaro , Giovanni Montani

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

We aim at the construction of dark energy models without exotic matter but with a phantom-like equation of state (an effective phantom phase). The first model we consider is decaying vacuum cosmology where the fluctuations of the vacuum are…

High Energy Physics - Theory · Physics 2009-09-17 Emilio Elizalde , Shin'ichi Nojiri , Sergei D. Odintsov , Peng Wang

In this article, we have discussed the results of our investigation. We consider an anisotropic viscous cosmological model of (LRS) Bianchi type I spacetime universe filled with a viscous fluid under $f(Q)$ gravity. We have studied the…

General Relativity and Quantum Cosmology · Physics 2024-08-14 Anirudh Pradhan , Archana Dixit , Dinesh Chandra Maurya