Bulk viscous matter and recent acceleration of the universe based on causal viscous theory

Mohan, N D Jerin; Sasidharan, Athira; Mathew, Titus K.

doi:10.1140/epjc/s10052-017-5428-y

Cited by 66 publications

(51 citation statements)

References 54 publications

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“…It has been argued that if cosmic fluid is not perfect but viscous, then its effective pressure, P + Π B may turn negative and change the solution of Einstein's equation, thereby affecting the cosmic evolution of the Universe, leading to an inflation like behaviour [9][10][11][12]. Similar arguments have been made in the context of currently observed cosmic acceleration [13][14][15][16]. It have been also shown that the bulk viscosity can unify the dark sectors.…”

Section: Several Other Independent Observations Such As Baryon Acoustmentioning

confidence: 79%

Viscous self interacting dark matter cosmology for small redshift

Atreya

Bhatt

Mishra

2019

J. Cosmol. Astropart. Phys.

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The viscosity of dark matter in cosmological models may cause an accelerated expansion and when this effect is sufficiently large, it can explain the dark energy. In this work, attributing the origin of viscosity to self-interaction of dark matter, we study the viscous cosmology at small redshift (0 ≤ z ≤ 2.5). Assuming the cluster scale to be virialized and by modeling a power law behavior of velocity gradients, we calculate the Hubble expansion rate, H(z) and the deceleration parameter, q(z). We then perform a χ 2 analysis to estimate the best fit model parameters. By using the best fit values, we explain the cosmic chronometer and type Ia supernova data. We conclude that if the dissipative effects become prominent only at the late time of cosmic evolution and are smaller at higher redshift, we can explain the observational data without requiring any dark energy component. Our analysis is independent of any specific model of self interacting dark matter.

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Section: Several Other Independent Observations Such As Baryon Acoustmentioning

confidence: 79%

Viscous self interacting dark matter cosmology for small redshift

Atreya

Bhatt

Mishra

2019

J. Cosmol. Astropart. Phys.

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“…Our novel solution generalizes the exact solution found in [17], for the particular values s = 1/2, γ = 1, where the expression τ = ξ/ρ for the relaxation time was used. In this article, the solution displays a decelerated phase an exponential expansion for late times, corresponding to a de Sitter phase.…”

Section: Introductionmentioning

confidence: 74%

“…In the above equations q 0 is the deceleration parameter at the present time t = t 0 , and the conditions a 0 = 1 and C 1 + C 2 = 1 have been set. This solution was previously found and discussed in [17], but with a particular relation for the relaxation time of the form ξ 0 ρ s−1 (which correspond to α = ξ 0 for our), instead of the more general relation as Eq. ( 7), in which the causality condition 0 < ≤ 1 is imposed.…”

Section: The Particular Case γ =mentioning

confidence: 83%

Exact analytical solution for an Israel-Stewart Cosmology

Cruz¹,

González²,

Palma³

2018

Preprint

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In this article we report a novel analytic solution for a cosmological model with a matter content described by a one component dissipative fluid, in the framework of the causal Israel-Stewart theory. Some physically well motivated analytical relations for the bulk viscous coefficient, the relaxation time and a bariotropic equation of state are postulated. We study within the parameter space, which label the solution, a suited region compatible with an accelerated expansion of the universe for late times, as well as stability properties of the solution at the critical parameter values γ = 1 and for s = 1/2. We study as well the consequences that arise from the positiveness of the entropy production along the time evolution. In general, the accelerated expansion at late times is only possible when ≥ 1/18, which implies a very large non-adiabatic contribution the speed of sound.

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“…It is worthy to mention that if we consider the limit case ω = 0 in the differential equation written in (5), we obtain the non-relativistic or DM case (γ = 1) explored in Ref. [30].…”

Section: Preliminaries Of the Israel-stewart Theorymentioning

confidence: 91%

Testing a non linear solution of the Israel-Stewart theory with supernovae

Crúz¹,

Cruz²,

González³

et al. 2021

Preprint

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In this work we test the capability of an exact solution found in the framework of a non linear extension of the Israel-Stewart theory to fit the supernovae Ia data. This exact solution is a generalization of one previously found in the context of the near equilibrium description of dissipative processes, where a dissipative unified dark matter model is studied, considering that such generalized solution does not represent the full regime of the non linear picture. We restrict the solution to the case where a positive entropy production is guaranteed. It is found that for some specific values of the parameter that characterizes the non linear effects, namely k, the model fits the supernovae Ia data slightly better than the ΛCDM model.

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Bulk viscous matter and recent acceleration of the universe based on causal viscous theory

Cited by 66 publications

References 54 publications

Viscous self interacting dark matter cosmology for small redshift

Viscous self interacting dark matter cosmology for small redshift

Exact analytical solution for an Israel-Stewart Cosmology

Testing a non linear solution of the Israel-Stewart theory with supernovae

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