Stability of viscous fluid in Bianchi type-VI model with cosmological constant

Sadeghi, J.; Amani, Alireza; Tahmasbi, N.

doi:10.1007/s10509-013-1579-y

Cited by 19 publications

(9 citation statements)

References 31 publications

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“…For that the universe is considered more realistic, we take the bulk viscosity fluid instead of the perfect fluid. In this case, the bulk viscosity creates internal friction that converts the kinetic energy of the particles into heat [99][100][101][102]. This in turn can be an appropriate idea to describe the accelerated universe in late time.…”

Section: Introductionmentioning

confidence: 99%

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

Mahichi,

Amani,

Ramzanpour

2021

Preprint

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In this paper, we study the F (R, G) gravity model with an interacting model by flat-FRW metric in a viscous fluid. We consider that the universe dominates with components of dark matter and dark energy. This means that the dark matter component derives from Extended Bose-Einstein Condensate (EBEC) and the components of dark energy arise from the F (R, G) gravity. After obtaining the Einstein equation, the energy density and the pressure of dark energy are written in terms of the geometries of the curvature and the Gauss-Bonnet terms, and components of dark matter and viscous fluid. Also, the corresponding continuity equations are written with the presence of interaction terms. In what follows, we employ the EBEC regime instead of the normal dark matter by the dark matter Equation of State (EoS) as p dm = αρ dm + βρ 2 dm , which arises from the gravitational form. The EoS can be expressed from the perspective of the virial expansion, in which the first and second terms represent normal dark matter and quantum ground state. Next, the corresponding Friedmann equations reconstruct in terms of the redshift parameter, then by using the scenario of the power-law cosmology for the scale factor, we fit the present model with the Hubble amounts of 51 supernova data by the likelihood analysis. In that case, we acquire the cosmological parameters of dark energy in terms of the redshift parameter, and by plotting these graphs, we see that the universe is currently undergoing an accelerated expansion phase.Finally, we investigate the stability of the present model with the sound speed parameter.

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Section: Introductionmentioning

confidence: 99%

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

Mahichi,

Amani,

Ramzanpour

2021

Preprint

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“…In addition, for a more realistic universe, we consider an anisotropic fluid as another category in this regard, i.e., the universe is dominated the f (T, B) scenario with the viscous fluid. [72][73][74][75]. This is a motivation to study the dark energy with bulk viscosity on the interactive f (T, B) scenario by correspondence to the new agegraphic.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of the viscous $f(T, B)$ gravity in the new agegraphic dark energy model

Pourbagher,

Amani

2020

Preprint

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In this paper, we first obtain the energy density by the approach of the new agegraphic dark energy model, and then the f (T, B) gravity model is studied as an alternative to the dark energy in a viscous fluid by flat-FRW background, in which T and B are torsion scalar and boundary term. The Friedmann equations will obtain in the framework of modified teleparallel gravity by tetrad components. We consider that the universe dominates with components such as matter and dark energy by an interacting model. The Hubble parameter is parameterized by the power-law for the scale factor, and then we fit the corresponding Hubble parameter with observational data constraints. The variation of the equation of state (EoS) for dark energy is plotted as a function of the redshift parameter, and the accelerated expansion of the universe is explored.In what follows, the stability of the model is also studied on the base of the sound speed parameter. Finally, the generalized second law of thermodynamics is investigated by entropies of inside and on the boundary of the apparent horizon in thermodynamics equilibrium.

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“…In addition to the aforesaid theories, the existence of anisotropic fluid is another factor in the variation of cosmic acceleration. The most important models of anisotropic fluid are Bianchi model and viscous fluid model [74][75][76][77]. For this purpose, we will consider viscous fluid in this job, namely, that the universe is dominated by the viscous fluid.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics and stability of $f(T,B)$ gravity with viscous fluid by observational constraints

Pourbagher,

Amani

2019

Preprint

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In this paper, we study the model of f (T, B) gravity with viscous fluid in flat-FRW metric, in which T and B are torsion scalar and boundary term, respectively. We obtain the Friedmann equations in the framework of modified teleparallel gravity by tetrad components. We consider an interacting model between matter and dark energy so that universe dominates by viscous fluid. Then, we write the corresponding cosmological parameters in terms of the redshift parameter, and, we parameterize the Hubble parameter with experimental data. In what follows, we plot the corresponding cosmological parameters for dark energy components in terms of redshift, thereafter we investigate the accelerated expansion of the universe. Moreover, we discuss the stability of the model by using the sound speed parameter. Finally, we investigate the validity of the generalized second law of thermodynamics.

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Stability of viscous fluid in Bianchi type-VI model with cosmological constant

Cited by 19 publications

References 31 publications

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

Extended Bose-Einstein condensate dark matter in viscous Gauss-Bonnet gravity

Thermodynamics of the viscous $f(T, B)$ gravity in the new agegraphic dark energy model

Thermodynamics and stability of $f(T,B)$ gravity with viscous fluid by observational constraints

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