Probing bulk viscous matter-dominated models with gamma-ray bursts

Montiel, Ariadna; Bretón, Nora

doi:10.1088/1475-7516/2011/08/023

Cited by 25 publications

(17 citation statements)

References 79 publications

(130 reference statements)

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“…4 we see that dark structures are severely suppressed for the valueξ = 1.5. Note that in this case the background expansion is not accelerated [23][24][25][26]. The dissipative mechanism present in the bulk viscous fluid avoids the formation of viscous dark matter halos in the unified scenario.…”

Section: B Bulk Viscous Fluidmentioning

confidence: 99%

Spherical collapse for unified dark matter models

2014

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We study the non-linear spherical "top hat" collapse for Chaplygin and viscous unified cosmologies. The term unified refers to models where dark energy and dark matter are replaced by one single component. For the generalized Chaplygin gas (GCG) we extend previous results of [R. A. A. Fernandes et al. Physical Review D 85, 083501 (2012)]. We discuss the differences at non-linear level between the GCG with α = 0 and the ΛCDM model. We show that both are indeed different. The bulk viscous model which differs from the GCG due to the existence of non-adiabatic perturbations is also studied. In this case, the clustering process is in general suppressed and the viable parameter space of the viscous model that accelerates the background expansion does not lead to collapsed structures. This result challenges the viability of unified viscous models.

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Section: B Bulk Viscous Fluidmentioning

confidence: 99%

Spherical collapse for unified dark matter models

2014

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“…Indeed, an update has been made recently of the sample of GRBs now consisting of 109 objects [32]. In [32,33] new calibrations have been developed in order to use GRBs in cosmological tasks.…”

Section: Grbs: Wang 2008 Data Setmentioning

confidence: 99%

Observational constraints on electromagnetic Born-Infeld cosmology

Bretón

Lazkoz

Montiel

2012

J. Cosmol. Astropart. Phys.

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The cosmological model consisting of an electromagnetic Born-Infeld (BI) field coupled to a Robertson-Walker geometry is tested with the standard probes of SNIa, GRBs and direct Hubble parameter. The analysis shows that the inclusion of the nonlinear electromagnetic component does not contribute in a significative way to the observed expansion. The BI electromagnetic matter is considered with an abundance of ΩBI , that our best fit leads to ΩBI = 0.037 when tested with SNIa and the Hubble parameter data (0.1 < z < 1.75); while when tested with GRBs the result is of ΩBI = 0.304, which may indicate that this electrodynamics was important at epochs close to the appearance of large structure (z ≈ 7), although this late result has not as much reliability as that corresponding to the first two probes, since we know that the dispersion in GRBs data is still considerable. In view of these results we can rule out the electromagnetic Born-Infeld matter as the origin of the present accelerated expansion, this conclusion concerns exclusively the Born-Infeld theory.arXiv:1209.2107v1 [astro-ph.CO]

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“…The dark energy phenomenon as an effect of the bulk viscosity in the cosmic medium has been first investigated in [48]. All these cited works are pioneer papers on the cosmological bulk viscosity, but it is also worth noting some recent applications of viscous fluids as candidates for dark matter [49], dark energy [50][51][52][53][54] or unified models [55][56][57][58][59][60], i.e., when a single substance plays the role of both dark matter and dark energy simultaneously. Indeed, it has been shown that for an appropriate viscosity coefficient, an accelerating cosmology can be achieved without the need of a cosmological constant [61][62][63][64].…”

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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Probing bulk viscous matter-dominated models with gamma-ray bursts

Cited by 25 publications

References 79 publications

Spherical collapse for unified dark matter models

Spherical collapse for unified dark matter models

Observational constraints on electromagnetic Born-Infeld cosmology

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

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