THE GENERALIZED CHAPLYGIN GAS MODEL WITH INTERACTION

2007 ◽  
Vol 16 (10) ◽  
pp. 1601-1609 ◽  
Author(s):  
YABO WU ◽  
SONG LI ◽  
HAI YANG ZHONG ◽  
LEI LI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Phantom Divide ◽  
Big Rip ◽  
The Future ◽  
Two Fluid

A two-fluid generalized Chaplygin gas (GCG) model including two different cases is considered in this paper. Concretely, the evolution of the GCG model with interaction is discussed and the statefinder diagnostic for the GCG models is performed, respectively. By analysis, we show that the effective state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of GCG will be like ΛCDM in the future and therefore our Universe will not end up with the Big Rip in the future. In addition, we find that the statefinder diagnostic can differentiate the GCG model with or without interaction. Also, trajectories of both the GCG model mixed with cold dark matter (CDM) and the pure GCG model in the parameter plane are illustrated to be significantly different.

A VARIABLE MODIFIED CHAPLYGIN GAS MODEL WITH INTERACTION

2009 ◽  
Vol 18 (12) ◽  
pp. 1851-1862 ◽  
Author(s):  
LILI XING ◽  
YUANXING GUI ◽  
CHUNYAN WANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Phantom Divide ◽  
Energy Models ◽  
Big Rip ◽  
Variable Modified Chaplygin Gas ◽  
The Future

We consider in this paper a variable modified Chaplygin gas (VMCG) model for describing the unification of dark energy and dark matter, in which dark energy interacts with dark matter. Concretely, the evolution of the VMCG model with interaction is discussed and the statefinder diagnostic for the model is performed. By analysis, we find that the effective state parameter of dark energy can cross the phantom divide wΛ= -1 and our universe will not end up with a Big Rip in the future. Furthermore, we perform a statefinder analysis on this scenario and show the discrimination between this scenario and other dark energy models.

THE MODIFIED CHAPLYGIN GAS AS A UNIFIED DARK SECTOR MODEL

2007 ◽  
Vol 22 (11) ◽  
pp. 783-790 ◽  
Author(s):  
YABO WU ◽  
SONG LI ◽  
JIANBO LU ◽  
XIUYI YANG
Keyword(s):  
Dark Energy ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Modified Chaplygin Gas ◽  
Dark Sector ◽  
Phantom Divide ◽  
Sector Model ◽  
Energy Models ◽  
Big Rip ◽  
The Future

A modified Chaplygin gas (MCG) model of unifying dark energy and dark matter is considered in this paper. Concretely, the evolution of such a unified dark sector model is studied and the statefinder diagnostic to the MCG model is performed in our model. By analysis, it is shown that the state parameter of dark energy can cross the so-called phantom divide ω = -1, the behavior of MCG will be like ΛCDM in the future and therefore our universe will not end up with Big Rip in the future. In addition, we plot the evolution trajectory of the MCG model in the statefinder parameter r–s plane and show the discrimination between this scenario and other dark energy models.

scholarly journals Study of thermal stability for different dark energy models

2019 ◽  
Vol 16 (11) ◽  
pp. 1950171
Author(s):  
Abdulla Al Mamon ◽  
Pritikana Bhandari ◽  
Subenoy Chakraborty
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Point Of View ◽  
Frw Universe ◽  
Generalized Chaplygin Gas ◽  
Dark Fluid ◽  
Energy Models

In this work, we have made an attempt to investigate the dark energy possibility from the thermodynamical point of view. For this purpose, we have studied thermodynamic stability of three popular dark energy models in the framework of an expanding, homogeneous, isotropic and spatially flat FRW Universe filled with dark energy and cold dark matter. The models considered in this work are Chevallier–Polarski–Linder (CPL) model, Generalized Chaplygin Gas (GCG) model and Modified Chaplygin Gas (MCG) model. By considering the cosmic components (dark energy and cold dark matter) as perfect fluid, we have examined the constraints imposed on the total equation of state parameter ([Formula: see text]) of the dark fluid by thermodynamics and found that the phantom nature ([Formula: see text]) is not thermodynamically stable. Our investigation indicates that the dark fluid models (CPL, GCG and MCG) are thermodynamically stable under some restrictions of the parameters of each model.

THE EVOLUTION OF GENERALIZED CHAPLYGIN GAS

2006 ◽  
Vol 21 (15) ◽  
pp. 1233-1239 ◽  
Author(s):  
YABO WU ◽  
XUEMEI DENG ◽  
JIANBO LU ◽  
SONG LI ◽  
XIUYI YANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Deceleration Parameter ◽  
Critical Density ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Big Rip ◽  
The Future ◽  
The Universe

We consider the generalized Chaplygin gas (GCG) proposal for the unification of dark matter and dark energy with p = pdeand ρ = ρdm+ρde. The unified equation of state for GCG has been obtained: [Formula: see text]. On the basis of the function χ(z), some cosmological quantities such as the fractional contributions of different components of the universe Ωi(i respectively denotes baryons, dark matter and dark energy) to the critical density, the equation of state for dark energy ωde, the deceleration parameter q are all obtained, which are consistent with observations. In addition, the transition from deceleration to acceleration is described in our model. We find that the behavior of GCG will be like ΛCDM in the future. So, it has been ruled out in our model that our universe will end up with Big Rip in the future.

scholarly journals TOWARDS CLASSIFICATION OF SIMPLE DARK ENERGY COSMOLOGICAL MODELS

2007 ◽  
Vol 04 (02) ◽  
pp. 313-323 ◽  
Author(s):  
MAREK SZYDLOWSKI ◽  
ALEKSANDRA KUREK
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Friedmann Equation ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Cosmological Time ◽  
Energy Models ◽  
State Formula ◽  
The Universe

We characterize a class of simple FRW models filled by both dark energy and dark matter in notion of a single potential function of the scale factor a(t); t is the cosmological time. It represents the potential of a fictitious particle — Universe moving in 1-dimensional well V(a) which the positional variable mimics the evolution of the Universe. Then the class of all dark energy models (called a multiverse) can be regarded as a Banach space naturally equipped in the structure of the Sobolev metric. In this paper, we explore the notion of C1 metric introduced in the multiverse which measures distance between any two dark energy models. If we choose cold dark matter as a reference, then we can find how far apart are different models offering explanation of the present accelerating expansion phase of the Universe. We consider both models with dark energy (models with the generalized Chaplygin gas, models with variable coefficient equation of state [Formula: see text] parameterized by redshift z, models with phantom matter) as well as models based on some modification of Friedmann equation (Cardassian models, Dvali–Gabadadze–Porrati brane models). We argue that because observational data still favor the ΛCDM model, all reasonable dark energy models should belong to the nearby neighborhood of this model.

INTERACTING GENERALIZED CHAPLYGIN GAS MODEL WITH HOLOGRAPHIC DARK ENERGY

2009 ◽  
Vol 24 (25) ◽  
pp. 2013-2024 ◽  
Author(s):  
YA BO WU ◽  
HUAN HUAN FU ◽  
FANG YUAN CHENG ◽  
JUN WANG ◽  
WEI QIANG YANG ◽  
...  
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cold Dark Matter ◽  
Holographic Dark Energy ◽  
Chaplygin Gas ◽  
Density Parameter ◽  
Coupling Constant ◽  
Generalized Chaplygin Gas ◽  
Dark Energy Component ◽  
Evolution Laws

In this paper we consider the interacting generalized Chaplygin gas model as a unified scheme, in which the holographic dark energy as the dark energy component interacts with the cold dark matter with wdm= 0. Concretely, we mainly discuss the two kinds of interactions between the dark energy and dark matter, and give the evolution trajectories of density parameter and equation of state of dark energy as well as the decelerate parameter. By analysis, we show that in both cases of Q = 3bHρdeand Q = 3bHρGCG, the evolution laws and the present values of Ωde, wdeand q are compatible with the astronomical observations, but the effects of the coupling constant and holographic constant on them are completely different.

scholarly journals BAYESIAN STATISTICS AND PARAMETER CONSTRAINTS ON THE GENERALIZED CHAPLYGIN GAS MODEL USING SNeIa DATA

2005 ◽  
Vol 14 (05) ◽  
pp. 775-796 ◽  
Author(s):  
R. COLISTETE ◽  
J. C. FABRIS ◽  
S. V. B. GONÇALVES
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Hubble Constant ◽  
State Parameter ◽  
Chaplygin Gas ◽  
Accelerating Universe ◽  
Generalized Chaplygin Gas ◽  
Age Of The Universe ◽  
Parameter Constraints ◽  
The Universe

The type Ia supernovae ( SNe Ia ) observational data are used to estimate the parameters of a cosmological model with cold dark matter and the generalized Chaplygin gas model (GCGM). The GCGM depends essentially on five parameters: the Hubble constant, the parameter [Formula: see text] related to the velocity of the sound, the equation of state parameter α, the curvature of the Universe and the fraction density of the generalized Chaplygin gas (or the cold dark matter). The parameter α is allowed to take negative values and to be greater than one. The Bayesian parameter estimation yields [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], where t0 is the age of the Universe and q0 is the value of the deceleration parameter today. Our results indicate that a Universe completely dominated by the generalized Chaplygin gas is favored, which reinforces the idea that the this gas may unify the description for dark matter and dark energy, at least as far as the SNe Ia data is concerned. A closed and accelerating Universe is also favored. The traditional Chaplygin gas model (CGM), α = 1 is not ruled out, even if it does not give the best-fitting. Particular cases with four or three independent free parameters are also analyzed.

EVOLUTION OF VARIABLE MODIFIED CHAPLYGIN GAS MODEL

2009 ◽  
Vol 24 (09) ◽  
pp. 683-691 ◽  
Author(s):  
LILI XING ◽  
YUANXING GUI ◽  
LIXIN XU ◽  
JIANBO LU
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Early Time ◽  
State Parameter ◽  
Growth Index ◽  
Chaplygin Gas ◽  
The State ◽  
Modified Chaplygin Gas ◽  
Phantom Divide ◽  
Variable Modified Chaplygin Gas

We consider a variable modified Chaplygin gas (VMCG) model with unified dark energy and dark matter. Some cosmological quantities are studied, such as the state parameter of dark energy wde, the fractional energy densities Ωi(i respectively denotes baryons, dark matter, dark energy), the deceleration parameter q and the growth index f. By analysis, we find that the state parameter of dark energy can cross the phantom divide wΛ= -1, the behavior of VMCG is similar to radiation in the early time and will be quinessence model in the future. Therefore the universe will not end up with Big Rip.

scholarly journals DARK MATTER TO DARK ENERGY TRANSITION IN k-ESSENCE COSMOLOGIES

2005 ◽  
Vol 20 (27) ◽  
pp. 2075-2082 ◽  
Author(s):  
L. P. CHIMENTO ◽  
MÓNICA FORTE ◽  
RUTH LAZKOZ
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Kinetic Energy ◽  
Speed Of Sound ◽  
Energy Transition ◽  
Chaplygin Gas ◽  
Large Set ◽  
Generalized Chaplygin Gas ◽  
General Terms ◽  
Transient Models

We implement the transition from dark matter to dark energy in k-essence cosmologies for a very large set of kinetic functions F, in a way alternative to recent proposals which use generalized Chaplygin gas and transient models. Here we require that the pressure admits a power-law expansion around some value of the kinetic energy where the pressure vanishes. In addition, for suitable values of the parameters of the model, the speed of sound of the dark matter will be low. We first present the discussion in fairly general terms, and later consider for illustration two examples.

scholarly journals ON THE GENERALIZED CHAPLYGIN GAS: WORSE THAN A BIG RIP OR QUIETER THAN A SUDDEN SINGULARITY?

2008 ◽  
Vol 17 (12) ◽  
pp. 2269-2290 ◽  
Author(s):  
MARIAM BOUHMADI-LÓPEZ ◽  
PEDRO F. GONZÁLEZ-DÍAZ ◽  
PRADO MARTÍN-MORUNO
Keyword(s):  
Chaplygin Gas ◽  
Brane World ◽  
Generalized Chaplygin Gas ◽  
The Past ◽  
Big Rip ◽  
Infrared Cutoff ◽  
The Future

Although it has been believed that models with generalized Chaplygin gas (GCG) do not contain singularities, in previous work we have studied how a big freeze could take place in some kinds of phantom-generalized Chaplygin gas. In the present work, we study some types of generalized Chaplygin gas in order to show how different sorts of singularities could appear in such models, either in the future or in the past. We point out that (i) singularities may not originate from the phantom nature of the fluid, and (ii) if initially the tension of the brane in a brane-world Chaplygin model is large enough, then an infrared cutoff appears in the past.

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