Bulk-viscosity-driven inflationary model

Waga, I.; Falcão, R. C.; Chanda, R.

doi:10.1103/physrevd.33.1839

Cited by 81 publications

(53 citation statements)

References 13 publications

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“…This approach has been explored in the literature through the moda e-mail: yoelsy.leyva@uta.cl eling of bulk viscosity in ordinary matter fluids [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] in the context of Eckart [26] or linear [27] and non-linear [28,29] Israel-Stewart theories.…”

Section: Introductionmentioning

confidence: 99%

Bulk viscosity, interaction and the viability of phantom solutions

Leyva¹,

Sepúlveda²

2017

Eur. Phys. J. C

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We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat FriedmannRobertson-Walker (FRW) Universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an imperfect fluid having bulk viscosity. We also introduce an interaction term between the dark matter and dark energy components. Considering that the bulk viscosity is proportional to the dark matter energy density and imposing a complete cosmological dynamics, we find bounds on the bulk viscosity in order to reproduce a matterdominated era (MDE). This constraint is independent of the interaction term. Some late time phantom solutions are mathematically possible. However, the constraint imposed by a MDE restricts the interaction parameter, in the phantom solutions, to a region consistent with a null value, eliminating the possibility of late time stable solutions with w < −1. From the different cases that we study, the only possible scenario, with bulk viscosity and interaction term, belongs to the quintessence region. In the latter case, we find bounds on the interaction parameter compatible with latest observational data.

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Section: Introductionmentioning

confidence: 99%

Bulk viscosity, interaction and the viability of phantom solutions

Leyva¹,

Sepúlveda²

2017

Eur. Phys. J. C

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“…Misner (1967Misner ( , 1968 suggested that strong dissipative due to the neutrino viscosity may considerably reduce the anisotropy of the black-body radiation. Viscosity mechanism in cosmology can explain the anomalously high entropy per baryon in B. Saha ( ) Laboratory of Information Technologies, Joint Institute for Nuclear Research, Dubna 141980, Russia e-mail: bijan@jinr.ru the present universe (Weinberg 1972a(Weinberg , 1972b. Bulk viscosity associated with the grand-unified-theory phase transition (Langacker 1981) may lead to an inflationary scenario (Waga et al 1986;Pacher et al 1987;Guth 1981).…”

Section: Introductionmentioning

confidence: 98%

Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions

Saha

2007

Astrophys Space Sci

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We consider a system of nonlinear spinor and a Bianchi type I gravitational fields in presence of viscous fluid. The nonlinear term in the spinor field Lagrangian is chosen to be λF , with λ being a self-coupling constant and F being a function of the invariants I an J constructed from bilinear spinor forms S and P . Self-consistent solutions to the spinor and BI gravitational field equations are obtained in terms of τ , where τ is the volume scale of BI universe. System of equations for τ and ε, where ε is the energy of the viscous fluid, is deduced. This system is solved numerically for some special cases.

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“…In the context of inflation, it has been known since a long time ago that an imperfect fluid with bulk viscosity can produce an acceleration without the need of a cosmological constant or some scalar field. An inflationary epoch driven by bulk viscous pressure has also been proposed in the 1980s [44][45][46][47]. All these works have analyzed the role played by the bulk viscosity in the early universe.…”

Section: Introductionmentioning

confidence: 99%

Friedmann model with viscous cosmology in modified $$f(R,T)$$ f ( R , T ) gravity theory

2014

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In this paper, we introduce the bulk viscosity in the formalism of modified gravity theory in which the gravitational action contains a general function f (R, T ), where R and T denote the curvature scalar and the trace of the energy-momentum tensor, respectively, within the framework of a flat Friedmann-Robertson-Walker model. As an equation of state for a prefect fluid, we take p = (γ − 1)ρ, where 0 ≤ γ ≤ 2 and a viscous term as a bulk viscosity due to the isotropic model, of the form ζ = ζ 0 + ζ 1 H , where ζ 0 and ζ 1 are constants, and H is the Hubble parameter. The exact non-singular solutions to the corresponding field equations are obtained with non-viscous and viscous fluids, respectively, by assuming a simplest particular model of the form of f (R, T ) = R + 2 f (T ), where f (T ) = αT (α is a constant). A big-rip singularity is also observed for γ < 0 at a finite value of cosmic time under certain constraints. We study all possible scenarios with the possible positive and negative ranges of α to analyze the expansion history of the universe. It is observed that the universe accelerates or exhibits a transition from a decelerated phase to an accelerated phase under certain constraints of ζ 0 and ζ 1 . We compare the viscous models with the non-viscous one through the graph plotted between the scale factor and cosmic time and find that the bulk viscosity plays a major role in the expansion of the universe. A similar graph is plotted for the deceleration parameter with non-viscous and viscous fluids and we find a transition from decelerated to accelerated phase with some form of bulk viscosity.

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Bulk-viscosity-driven inflationary model

Cited by 81 publications

References 13 publications

Bulk viscosity, interaction and the viability of phantom solutions

Bulk viscosity, interaction and the viability of phantom solutions

Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions

Friedmann model with viscous cosmology in modified $$f(R,T)$$ f ( R , T ) gravity theory

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