Interacting modified Chaplygin gas cosmology with varying viscosity

2014 ◽  
Vol 92 (11) ◽  
pp. 1470-1473
Author(s):  
K. Karimiyan ◽  
J. Naji
Keyword(s):  
Energy Density ◽  
Bulk Viscosity ◽  
Deceleration Parameter ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Baryonic Matter ◽  
Modified Chaplygin Gas ◽  
Hubble Expansion ◽  
Interaction Interaction ◽  
Varying Viscosity

We study interacting modified Chaplygin gas, which has shear and bulk viscosities. We assume bulk viscosity is a function of density, and also consider sign-changeable interaction. Interaction is assumed between modified Chaplygin gas and baryonic matter. Then, the effects of viscosities on the cosmological parameters, such as energy, density, Hubble expansion parameter, scale factor, and deceleration parameter, are investigated. We can consider this model as a toy model of our universe.

EFFECT OF SHEAR AND BULK VISCOSITIES ON INTERACTING MODIFIED CHAPLYGIN GAS COSMOLOGY

2014 ◽  
Vol 23 (02) ◽  
pp. 1450020 ◽  
Author(s):  
J. NAJI ◽  
B. POURHASSAN ◽  
ALI R. AMANI
Keyword(s):  
Energy Density ◽  
Deceleration Parameter ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Scale Factor ◽  
Modified Chaplygin Gas ◽  
Expansion Parameter ◽  
Hubble Expansion

In this paper, we study interacting modified Chaplygin gas (MCG) which has shear and bulk viscosities. We consider sign-changeable interaction between MCG and matter, then investigate the effects of shear and bulk viscosities on the cosmological parameters such as energy, density, Hubble expansion parameter, scale factor and deceleration parameter.

scholarly journals Interacting models of generalized Chaplygin gas and modified Chaplygin gas with barotropic fluid

2019 ◽  
Vol 34 (09) ◽  
pp. 1950064 ◽  
Author(s):  
Promila Biswas ◽  
Ritabrata Biswas
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Modified Chaplygin Gas ◽  
Interaction Coefficients ◽  
Generalized Chaplygin Gas ◽  
Barotropic Fluid

In this paper, we consider two different models of our present universe. We choose the models which consist of different sets of two separate fluids. The first one of each set tries to justify the late time acceleration and the second one is barotropic fluid. The former model considers our present time universe to be homogeneously filled up by Generalized Chaplygin Gas which is interacting with barotropic fluid. On the other hand, the latter model considers that the cosmic acceleration is generated by Modified Chaplygin Gas which is interacting with matter depicted by barotropic equation of state (EoS). For both the models, we consider the interaction term to vary proportionally with Hubble’s parameter as well as with the exotic matter/dark energy’s energy density. We find an explicit function form of the energy density of the cosmos which is found to depend on different cosmological parameters like scale factor, dark energy and barotropic fluid’s EoS parameters and other constants, like interacting constants, etc. We draw curves of effective EoS-s, different cosmological parameters like deceleration parameter q, statefinder parameters r and s with respect to the redshift z (for different values of dark energy and barotropic fluid parameters) and study them thoroughly. We compare two models as well as the nature of dependencies on these models’ interaction coefficients. We point out the particular redshift for which the universe may transit from a deceleration to acceleration phase. We tally all these values with different observational data. Here, we also analyze how this value of particular redshift does change for different values of interaction coefficients and different dark energy models.

scholarly journals Bulk Viscous Cosmological Model in Brans-Dicke Theory with New Form of Time Varying Deceleration Parameter

2017 ◽  
Vol 2017 ◽  
pp. 1-24
Author(s):  
G. P. Singh ◽  
Binaya K. Bishi
Keyword(s):  
Equation Of State ◽  
Cosmological Model ◽  
Bulk Viscosity ◽  
Deceleration Parameter ◽  
Chaplygin Gas ◽  
Time Varying ◽  
Modified Chaplygin Gas ◽  
Bulk Viscous ◽  
New Form ◽  
Frw Cosmological Model

We have presented FRW cosmological model in the framework of Brans-Dicke theory. This paper deals with a new proposed form of deceleration parameter and cosmological constant Λ. The effect of bulk viscosity is also studied in the presence of modified Chaplygin gas equation of state (p=Aρ-B/ρn). Furthermore, we have discussed the physical behaviours of the models.

scholarly journals Hubble Parameter Corrected Interactions in Cosmology

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
J. Sadeghi ◽  
M. Khurshudyan ◽  
M. Hakobyan ◽  
H. Farahani
Keyword(s):  
Linear Function ◽  
Interaction Parameter ◽  
Bulk Viscosity ◽  
Hubble Parameter ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Time Dependent ◽  
Modified Chaplygin Gas ◽  
And Behavior ◽  
The Universe

We make steps in a new direction by considering fluids with EoS of more general formF(ρ,P)=0. It is thought that there should be interaction between cosmic fluids, but this assumption for this stage carries only phenomenological character opening a room for different kinds of manipulations. In this paper we will consider a modification of an interactionQ, where we accept that interaction parameterb1(order of unity) inQ=3Hb1ρis time dependent and presented as a linear function of Hubble parameterHof the formb0+btH, wherebandb0are constants. We consider two different models including modified Chaplygin gas and polytropic gas which have bulk viscosity. Then, we investigate problem numerically and analyze behavior of different cosmological parameters concerning fluids and behavior of the universe.

New version of viscous Chaplygin gas cosmology with varying gravitational constant

2014 ◽  
Vol 92 (12) ◽  
pp. 1556-1561 ◽  
Author(s):  
J. Naji ◽  
S. Heydari ◽  
R. Darabi
Keyword(s):  
Energy Density ◽  
Bulk Viscosity ◽  
Gravitational Constant ◽  
Cosmological Parameters ◽  
Quadratic Equation ◽  
Chaplygin Gas ◽  
Dark Energy Density ◽  
Barotropic Fluid ◽  
Power Law Function ◽  
Varying Gravitational Constant

In this paper we consider a new version of Chaplygin gas cosmology that includes bulk viscosity and a varying gravitational constant. This new model of Chaplygin gas allows us to recover a barotropic fluid with a quadratic equation of state. Bulk viscosity is assumed to be a power law function of the energy density. We study the evolution of dark energy density numerically for several forms of scale factor and analytically under some assumptions corresponding to a late epoch of the universe. We discuss some cosmological parameters and fix them using recent observational data, such as those from the Background Imaging of Cosmic Extragalactic Polarization 2 (BICEP2) telescope.

scholarly journals Dynamical system analysis of FLRW models with Modified Chaplygin gas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ali Osman Yılmaz ◽  
Ertan Güdekli
Keyword(s):  
Dynamical System ◽  
Equation Of State ◽  
Energy Density ◽  
System Analysis ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
State Spaces ◽  
The Universe ◽  
Matter Energy ◽  
Far Future

AbstractWe investigate Friedmann–Lamaitre–Robertson–Walker (FLRW) models with modified Chaplygin gas and cosmological constant, using dynamical system methods. We assume $$p=(\gamma -1)\mu -\dfrac{A}{\mu ^\alpha }$$ p = ( γ - 1 ) μ - A μ α as equation of state where $$\mu$$ μ is the matter-energy density, p is the pressure, $$\alpha$$ α is a parameter which can take on values $$0<\alpha \le 1$$ 0 < α ≤ 1 as well as A and $$\gamma$$ γ are positive constants. We draw the state spaces and analyze the nature of the singularity at the beginning, as well as the fate of the universe in the far future. In particular, we address the question whether there is a solution which is stable for all the cases.

scholarly journals VISCOUS MODIFIED COSMIC CHAPLYGIN GAS COSMOLOGY

2013 ◽  
Vol 22 (09) ◽  
pp. 1350061 ◽  
Author(s):  
B. POURHASSAN
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Nonlinear Equation ◽  
Observational Data ◽  
Function Method ◽  
Chaplygin Gas ◽  
Time Dependent ◽  
Dark Energy Density ◽  
Hubble Expansion ◽  
Exponential Function Method

In this paper, we construct viscous modified cosmic Chaplygin gas as a model of dark energy. We use exponential function method to solve nonlinear equation and obtain time-dependent dark energy density. Then, we discuss Hubble expansion parameter and scale factor and fix them by using observational data. Effect of viscosity to the evolution of Universe is investigated. We also investigate stability of this theory.

CONSTRAINTS ON TRANSITION REDSHIFT AND DECELERATION PARAMETER FROM RECENT OBSERVATIONS

2008 ◽  
Vol 23 (25) ◽  
pp. 2067-2076 ◽  
Author(s):  
JIANBO LU ◽  
LIXIN XU ◽  
JIECHAO LI ◽  
HONGYA LIU
Keyword(s):  
Confidence Level ◽  
Deceleration Parameter ◽  
Mass Fraction ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
X Ray ◽  
Central Values ◽  
Λcdm Model ◽  
Best Fit

In this paper, the 1σ confidence level of transition redshift and present deceleration parameter are studied using modified Chaplygin gas (MCG) model from recent observations: the 182 Gold SNe Ia, three-year WMAP, SDSS baryon acoustic peak and X-ray gas mass fraction in clusters. Concretely, the best fit values of the transition redshift and present deceleration parameter with the 1σ confidence level are [Formula: see text] and [Formula: see text], which indicate the best fit values of zT and q0 for MCG case are surprisingly close to the central values given by Refs. 20 and 21. Furthermore, we plot the evolution of cosmological quantities from MCG model by using the best-fit parameters given by combining constraint, and compare them with ΛCDM model.

Modified Chaplygin gas equation of state on viscous dissipative extended holographic Ricci dark energy and the cosmological consequences

2016 ◽  
Vol 26 (06) ◽  
pp. 1750042 ◽  
Author(s):  
Surajit Chattopadhyay
Keyword(s):  
Dark Energy ◽  
Bulk Viscosity ◽  
Cold Dark Matter ◽  
Viscosity Coefficient ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Ricci Dark Energy ◽  
Dissipative Term ◽  
Generalized Second Law ◽  
The Universe

The present paper reports a study on modified Chaplygin gas (MCG)-based reconstruction scheme for extended holographic Ricci dark energy (EHRDE) in the presence of viscous type dissipative term. The dissipative effect has been described by using Eckart approach. Under the assumption that the universe is filled with MCG–EHRDE under the influence of bulk viscosity we have studied the cosmological dynamics, where the bulk viscosity coefficient has been chosen in a particular time varying form [Formula: see text], where [Formula: see text] and [Formula: see text] are constant coefficients and [Formula: see text] is the Hubble parameter. Furthermore, we have reconstructed the potential and dynamics of viscous MCG–EHRDE as scalar field. Thereafter we have studied the statefinder trajectories to discern its departure from [Formula: see text] cold dark matter ([Formula: see text]CDM) and finally investigated validity of the generalized second law (GSL) of thermodynamics considering event horizon as the enveloping horizon of the universe.

scholarly journals Interacting Quintessence Dark Energy Models in Lyra Manifold

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
M. Khurshudyan ◽  
J. Sadeghi ◽  
R. Myrzakulov ◽  
Antonio Pasqua ◽  
H. Farahani
Keyword(s):  
Dark Energy ◽  
Numerical Analysis ◽  
Cosmological Parameters ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Van Der Waals Gas ◽  
Lyra Manifold ◽  
Energy Models ◽  
Two Component ◽  
Quintessence Field

We consider two-component dark energy models in Lyra manifold. The first component is assumed to be a quintessence field while the second component may be a viscous polytropic gas, a viscous Van der Waals gas, or a viscous modified Chaplygin gas. We also consider the possibility of interaction between components. By using the numerical analysis, we study some cosmological parameters of the models and compare them with observational data.

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