FRW bulk viscous cosmology with modified Chaplygin gas in flat space

Saadat, Hassan; Pourhassan, B.

doi:10.1007/s10509-012-1268-2

Cited by 103 publications

(73 citation statements)

References 36 publications

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“…This model is subject of some brane world scenario Ranjit et al 2013aRanjit et al , 2013b, and holographic model of dark energy (Farooq et al 2010;Paul 2010;Sadeghi et al 2014a). Viscous modified Chaplygin gas also introduced by Pun et al (2008) and completed by the recent works (Pourhassan 2013;Saadat and Pourhassan 2013b;Benaoum 2014). The MCG equation of state (EoS) has two parts, the first term gives an ordinary fluid obeying a linear barotropic EoS, and the second term relates pressure to some power of the inverse of energy density.…”

Section: Introductionmentioning

confidence: 99%

Observational constraints on the extended Chaplygin gas inflation

Kahya

Pourhassan

2014

Astrophys Space Sci

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In this paper, we study extended Chaplygin gas as a candidate for inflation and predict the values of gas parameters for a physically viable cosmological model. The extended Chaplygin gas which proposed recently has n + 2 free parameters. When n = 1, there are three parameters which are corresponding to modified Chaplygin gas. Here we focus on the second order equation of state where n = 2, so we have generally four free parameters. Under some assumptions, we reduced free parameters of the model to the only one parameter and try to fix it using the dimensionless age parameter. Also we check validity of our calculations using recent observations of BICEP2.

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Section: Introductionmentioning

confidence: 99%

Observational constraints on the extended Chaplygin gas inflation

Kahya

Pourhassan

2014

Astrophys Space Sci

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“…As we demonstrate shortly in the following sections, we will be able to offer more freedom to the choice of model parameters. Let us note finally that, our approach does not imply any interaction between dark energy and dark matter, in terms of some generalized equation of state, as it was done for example in [63][64][65][66][67][68][69] and references therein. In our case, there is no interaction between matter and dark energy and the only existent interactions are the self interactions of matter, expressed in terms of a logarithmic or a power-law dependence on the matter-energy density.…”

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confidence: 99%

Late-time cosmological evolution in f ( R ) theories with ordinary and collisional matter

Oikonomou

Karagiannakis

2015

Class. Quantum Grav.

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We study the late time cosmological evolution of f (R) theories of modified gravity, with the matter content of the universe being that of collisional self interacting matter. We assume that the universe is described by a flat Friedmann-Lemaitre-RobertsonWalker metric and that it is matter and dark energy dominated. The results of our numerical analysis for a collisional matter f (R) theory are compared with those resulting from pressure-less matter f (R) theory and from the ΛCDM model. As we shall demonstrate, the resulting picture can vary from model to model, indicating that the effect of collisional matter in f (R) theories is strongly model dependent. Particularly, in a few cases, may give better fit to the ΛCDM model. In all studied cases, the effective equation of state parameter does not cross the phantom divide, both in the collisional matter and pressure-less matter f (R) theories. Finally, we thoroughly study the effects of collisional matter on one of the f (R) models that is known to provide a unified description of early time inflation and late time acceleration. The overall picture of the evolution of the universe is not drastically affected, apart from the matter era which is further enhanced with an additional matter energy density term, which is of leading order. However, a fully consistent description of the universe's evolution requires the introduction of a dark energy compensate in the total energy density, a concept very well known from the literature. * voiko@physics.auth.gr † nikar@auth.gr

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“…It is also possible to consider viscosity in above models [15][16][17][18][19][20][21][22][23][24][25]. Another way to study dark energy arises from holographic principle states that the number of degrees of freedom related directly to the entropy scales with the enclosing area of the system.…”

Section: +007mentioning

confidence: 99%

Interacting holographic extended Chaplygin gas and phantom cosmology in the light of BICEP2

2015

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Abstract:In this paper, we study the holographic dark energy density and interacting extended Chaplygin gas energy density in the Einstein gravity. We reconstruct the scalar field and the scalar potential describing the extended Chaplygin gas. In the special case, we obtain energy density and investigate some cosmological parameters. Assuming interaction between components we find energy density for some different parametrization of total EoS. We analyze tensor to scalar ratio and use recent observational data of BICEP2 to fix the model parameters.

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FRW bulk viscous cosmology with modified Chaplygin gas in flat space

Abstract: In this paper we study FRW bulk viscous cosmology in presence of modified Chaplygin gas. We write modified Friedmann equations due to bulk viscosity and Chaplygin gas and obtain time-dependent energy density for the special case of flat space.

Cited by 103 publications

References 36 publications

Observational constraints on the extended Chaplygin gas inflation

Observational constraints on the extended Chaplygin gas inflation

Late-time cosmological evolution in f ( R ) theories with ordinary and collisional matter

Interacting holographic extended Chaplygin gas and phantom cosmology in the light of BICEP2

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