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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

We explore flat {\Lambda}CDM models with bulk viscosity, and study the role of the bulk viscosity in the evolution of these universe models. The dynamical equations for these models are obtained and solved for some cases of bulk viscosity.…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-04 Nouraddin Mostafapoor , Oyvind Gron

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

Gravitational and hydrodynamical perturbations are analysed in a relativistic plasma containing a mixture of interacting fluids characterized by a non-negligible bulk viscosity coefficient. The energy-momentum transfer between the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Massimo Giovannini

Within the framework of Unimodular Gravity, we consider non-gravitational interactions between dark matter and dark energy. Particularly, we describe such interactions in the dark sector by considering diffusion models that couple the cold…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-31 Francisco X. Linares Cedeño , Ulises Nucamendi

We have studied bulk viscosity in the modified $f(Q, T)$ gravity theory formalism, where $Q$ represents the non-metricity and $T$ denotes the trace of energy-momentum tensor within a flat Friedmann-Lema\^{i}tre-Robertson-Walker metric…

General Relativity and Quantum Cosmology · Physics 2021-12-01 Simran Arora , S. K. J. Pacif , Abhishek Parida , P. K. Sahoo

We present and constrain a cosmological model where the only component is a pressureless fluid with bulk viscosity as an explanation for the present accelerated expansion of the universe. We study the particular model of a bulk viscosity…

General Relativity and Quantum Cosmology · Physics 2009-01-05 Arturo Avelino , Ulises Nucamendi

We consider the interacting holographic dark energy with new infrared cutoff (involving Hubble parameter and its derivative) in non-flat universe. In this context, we obtain the equation of state parameter which evolutes the universe from…

General Relativity and Quantum Cosmology · Physics 2015-06-12 M. Sharif , Abdul Jawad

In this work we perform some studies related to dark energy. Firstly, we propose a dynamical approach to explain the dark energy content of the universe. We assume that a massless scalar field couples to the Hubble parameter with some…

High Energy Physics - Phenomenology · Physics 2009-01-07 Fei Wang , Jin Min Yang

In this talk, we discuss one of the dissipative processes which likely take place in the Early Universe. We assume that the matter filling the isotropic and homogeneous background is to be described by a relativistic viscous fluid…

General Relativity and Quantum Cosmology · Physics 2011-10-03 A. Tawfik , T. Harko , H. Mansour , M. Wahba

We consider a unified dissipative dark fluid model. Our fluid contains an adiabatic part plus a bulk viscous one. The adiabatic part has the ability to asymptote between two power laws and so can interpolate between the dust and dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-16 Esraa Elkhateeb

In this paper, we have constructed the cosmological model of the universe in a two fluids environment with a newly developed mathematical formalism. In order to construct the model Binachi type V (BV) space time is considered with a time…

General Relativity and Quantum Cosmology · Physics 2019-01-23 B. Mishra , Pratik P Ray , R. Myrzakulov

The current Universe is composed by a mixture of relativistic species, baryonic matter, dark matter and dark energy which evolve in a non-trivial way at perturbative level. An advanced description of the cosmological dynamics should include…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 Winfried Zimdahl , Júlio Fabris , Hermano Velten , Ramón Herrera

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

Thermodynamic analyses of dark energy as a relativistic fluid indicates that this intriguing component of the universe mimics a bulk viscous pressure when the parameter of its barotropic equation of state varies with time. Since in…

General Relativity and Quantum Cosmology · Physics 2025-03-04 José Medeiros da Costa Netto , Heydson Henrique Brito da Silva

A model for the Universe is proposed whose constituents are: (a) a dark energy field modeled by a fermionic field non-minimally coupled with the gravitational field, (b) a matter field which consists of pressureless baryonic and dark matter…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. O. Ribas , F. P. Devecchi , G. M. Kremer

We consider the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a causal bulk viscous cosmological fluid, in the presence of variable gravitational and cosmological constants. The basic equation for the Hubble…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. K. Mak , J. A. Belinchon , T. Harko

Main aim of this work is to give a suitable explanation of present accelerating universe through an acceptable interactive dynamical cosmological model. A three-fluid cosmological model is introduced in the background of…

General Relativity and Quantum Cosmology · Physics 2022-02-16 Giridhari Deogharia , Mayukh Bandyopadhyay , Ritabrata Biswas

We investigate an interacting two-fluid cosmological model and introduce a scalar field representation by means of a linear combination of the individual energy densities. Applying the integrability condition to the scalar field equation we…

Astrophysics · Physics 2008-11-26 Luis Chimento , Monica Forte

In this paper, we study the cosmological evolution of a viscous dark energy model within the framework of $f(Q, C)$ gravity, utilizing a two-fluid approach. The model incorporates non-metricity and boundary contributions to the total…

General Relativity and Quantum Cosmology · Physics 2025-10-15 N. Myrzakulov , Anirudh Pradhan , S. H. Shekh