共查询到20条相似文献,搜索用时 15 毫秒
1.
A modified Chaplygin gas (MCG) model of unifying dark energy and dark matter is considered in this paper, in which dark energy
interacts with dark matter. Concretely, the evolution of such a unified dark sectors model is studied and the statefinder
diagnostic to the MCG model is performed in our model. By analysis, it is shown that the effective equation of state (EoS)
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. Furthermore, we plot the evolution trajectories of the MCG model in the statefinder parameter r–s plane and illustrate the discrimination between this scenario and the generalized Chaplygin gas (GCG) model. 相似文献
2.
G. C. Samanta 《International Journal of Theoretical Physics》2013,52(12):4389-4402
In this paper, author studied homogeneous and anisotropic Bianchi type-V universe filled with matter and holographic dark energy (DE) components. The exact solutions to the corresponding Einstein’s field equations are obtained for exponential and power-law volumetric expansion. The holographic dark energy (DE) EoS parameter behaves like constant, i.e. ω Λ =?1, which is mathematically equivalent to cosmological constant (Λ) for exponential expansion of the model, whereas the holographic dark energy (DE) EoS parameter behaves like quintessence for power-law expansion of the model. A correspondence between the holographic dark energy (DE) models with the quintessence dark energy (DE) is also established. Quintessence potential and dynamics of the quintessence scalar field are reconstructed, which describe accelerated expansion of the universe. The statefinder diagnostic pair {r,s} is adopted to characterize different phases of the universe. 相似文献
3.
Piyali Bagchi Khatua Ujjal Debnath 《International Journal of Theoretical Physics》2012,51(12):3701-3720
In this work, we have considered Cardassian Universe in Ho?ava-Lifshitz gravity. Four types of Cardassian Universe models i.e., polytropic/power law, modified polytropic, exponential and modified exponential models have been considered for accelerating models. The natures of statefinder parameters, deceleration parameter, Om diagnostic and EoS parameters have been investigated for all types of Cardassian models in Ho?ava-Lifshitz gravity. 相似文献
4.
M. Malekjani A. Khodam-Mohammadi 《International Journal of Theoretical Physics》2012,51(10):3141-3151
The interacting polytropic gas dark energy model is investigated from the viewpoint of statefinder diagnostic tool and w−w′ analysis. The dependency of the statefinder parameters on the parameter of the model as well as the interaction parameter between dark matter and dark energy is calculated. We show that different values of the parameters of model and different values of interaction parameter result different evolutionary trajectories in s−r and w−w′ planes. The polytropic gas model of dark energy mimics the standard ΛCDM model at the early time. 相似文献
5.
In this paper, we study the evolution of a spatially flat universe composed of Tsallis agegraphic dark energy(TADE) and a pressureless dark matter(DM), by assuming that there is a signchangeable interaction between TADE and DM. The density, deceleration parameter and the equation of state parameters(EoS) show satisfactory behaviors in the model. By analysis we find that the accelerated expansion of the universe can be achieved at the late time if model parameters δ2 and -2/3β0. Also, we investigate the interacting TADE model by means of statefinder diagnostic and w–w' analysis. 相似文献
6.
Mubasher Jamil 《International Journal of Theoretical Physics》2010,49(11):2829-2840
Motivated by several observational and theoretical developments concerning the variability of Newton’s gravitational constant
with time G(t), we calculate the varying G correction to the statefinder parameters for four models of dark energy namely interacting dark energy holographic dark energy,
new-agegraphic dark energy and generalized Chaplygin gas. 相似文献
7.
Piyali Bagchi Khatua Ujjal Debnath 《International Journal of Theoretical Physics》2012,51(4):1155-1172
We have considered the generalized holographic and generalized Ricci dark energy models for acceleration of the universe.
If the universe filled with only GHDE/GRDE the corresponding deceleration parameter, EOS parameter and statefinder parameters
have been calculated. Next we have considered that the mixture of GHDE/GRDE and dark matter in interacting and non-interacting
situations. Also the mixture of GHDE/GRDE and generalized Chaplygin gas have been analyzed during evolution of the universe.
The natures of above mentioned parameters have been investigated for interacting and non-interacting situations. Finally,
it follows that the prescribed models derive the acceleration of the universe. 相似文献
8.
Rahul Ghosh Surajit Chattopadhyay Ujjal Debnath 《International Journal of Theoretical Physics》2012,51(2):589-603
This work is motivated by the work of Kim et al. (Mod. Phys. Lett. A 23:3049, 2008), which considered the equation of state parameter for the new agegraphic dark energy based on generalized uncertainty principle
coexisting with dark matter without interaction. In this work, we have considered the same dark energy interacting with dark
matter in emergent, intermediate and logamediate scenarios of the universe. Also, we have investigated the statefinder, kerk and lerk parameters in all three scenarios under
this interaction. The energy density and pressure for the new agegraphic dark energy based on generalized uncertainty principle
have been calculated and their behaviors have been investigated. The evolution of the equation of state parameter has been
analyzed in the interacting and non-interacting situations in all the three scenarios. The graphical analysis shows that the
dark energy behaves like quintessence era for logamediate expansion and phantom era for emergent and intermediate expansions
of the universe. 相似文献
9.
We investigate observational constraint on the variable generalized Chaplygin gas (VGCG) model as the unification of dark matter and dark energy by using the Union supernovae sample and the baryon acoustic oscillations data. Based on the best fit parameters for VGCG model it is shown that the current value of equation of state for dark energy is w0de=−1.08<−1, and the universe will not end up with big rip in the future. In addition, we also discuss the evolution of several quantities in VGCG cosmology such as deceleration parameter, fractional density parameters, growth index and sound speed. Finally, the statefinder diagnostic is performed to discriminate the VGCG with other models. 相似文献
10.
The purpose of this paper is to discuss the evolution of modified holographic dark energy with variable G in non-flat Kaluza–Klein universe. We consider the non-interacting and interacting scenarios of the modified holographic
dark energy with dark matter and obtain the equation of state parameter through logarithmic approach. It turns out that the
universe remains in different dark energy eras for both cases. Further, we study the validity of the generalized second law
of thermodynamics in this scenario. We also justify that the statefinder parameters satisfy the limit of ΛCDM model. 相似文献
11.
Statefinder diagnostic is a useful method which can differ one dark energy model from each others. In this Letter, we apply this method to a holographic dark energy model from Ricci scalar curvature, called the Ricci dark energy model (RDE). We plot the evolutionary trajectories of this model in the statefinder parameter-planes, and it is found that the parameter of this model plays a significant role from the statefinder viewpoint. In a very special case, the statefinder diagnostic fails to discriminate LCDM and RDE models, thus we apply a new diagnostic called the Om diagnostic proposed recently to this model in this case in Appendix A and it works well. 相似文献
12.
Mubasher Jamil D. Momeni Ratbay Myrzakulov 《International Journal of Theoretical Physics》2013,52(9):3283-3294
In this paper, we have calculated the statefinder parameters for the Friedmann-Robertson-Walker (FRW) Universe in the gravitational framework of loop quantum cosmology (LQC). As examples, we study two types of dark energy models namely Holographic dark energy and New-Agegraphic dark energy. 相似文献
13.
M. Vijaya Santhi V. U. M. Rao Y. Aditya 《International Journal of Theoretical Physics》2017,56(2):362-371
A spatially homogeneous and anisotropic locally rotationally symmetric (LRS) Bianchi type-I Universe filled with matter and generalized ghost pilgrim dark energy (GGPDE) has been studied in general theory of relativity. To obtain determinate solution of the field equations we have used scalar expansion proportional to the shear scalar which leads to a relation between the metric potentials. Some well-known cosmological parameters (equation of state (EoS) parameter (ω Λ), deceleration parameter (q) and squared speed of sound \({v_{s}^{2}}\)) and planes (\(\omega _{\Lambda }-\dot {\omega }_{\Lambda }\) and statefinder) are constructed for obtained model. The discussion and significance of these parameters is totally done through pilgrim dark energy parameter (β) and cosmic time (t). 相似文献
14.
Locally rotationally symmetric Bianchi type I cosmological models are examined in the presence of dynamically anisotropic
dark energy and perfect fluid. We assume that the dark energy (DE) is minimally interacting, has dynamical energy density,
anisotropic equation of state parameter (EoS). The conservation of the energy-momentum tensor of the DE is assumed to consist
of two separately additive conserved parts. A special law is assumed for the deviation from isotropic EoS, which is consistent
with the assumption on the conservation of the energy-momentum tensor of the DE. Exact solutions of Einstein’s field equations
are obtained by assuming a special law of variation for the mean Hubble parameter, which yields a constant value of the deceleration
parameter. Geometrical and kinematic properties of the models and the behaviour of the anisotropy of the dark energy have
been carried out. The models give dynamically anisotropic expansion history for the universe that allows to fine tune the
isotropization of the Bianchi metric, hence the CMB anisotropy. 相似文献
15.
D. R. K. Reddy R. Santhi Kumar T. V. Pradeep Kumar 《International Journal of Theoretical Physics》2013,52(1):239-245
A dark energy model with EoS parameter is investigated in f(R,T) gravity in Bianchi type-III space-time in the presence of perfect fluid source. To obtain a determinate solution special law of variation for Hubble’s parameter proposed by Berman (Nuovo Cimento B 74:183, 1983) is used. We have also assumed that the scalar expansion is proportional to shear and the EoS parameter is proportional to skewness parameter. It is observed that the EoS parameter, skewness parameters in the model turn out to be functions of cosmic time. Some physical and kinematical properties of the model are also discussed. 相似文献
16.
In this paper bulk viscosity is introduced to describe the effects of cosmic non-perfect fluid on the cosmos evolution and to build the unified dark energy (DE) with (dark) matter models. Also we derive a general relation between the bulk viscosity form and Hubble parameter that can provide a procedure for the viscosity DE model building. Especially, a redshift dependent viscosity parameterζ∝λ0 +λ1(1+z)n proposed in the previous work [X.H. Meng and X. Dou, Commun. Theor. Phys. 52 (2009) 377] is investigated extensively in this present work. Further more we use the recently released supernova dataset
(the Constitution dataset) to constrain the model parameters. In order to differentiate the proposed concrete dark energy models from the well known $\Lambda$CDM model, statefinder diagnostic method is applied to this bulk viscosity model, as a complementary to the Om parameter diagnostic and the deceleration parameter analysis performed by us before. The DE model evolution behavior and tendency are shown in the plane of the statefinder diagnostic parameter pair {r,s} as axes where the fixed point represents theΛCDM model. The possible singularity property in this bulk viscosity
cosmology is also discussed to which we can conclude that in the different parameter regions chosen properly, this concrete viscosity DE model can have various late evolution behaviors and the late time singularity could be avoided. We also calculate the cosmic entropy in the bulk viscosity dark energy frame, and find that the total entropy in the viscosity DE model increases monotonously with respect to the scale factor evolution, thus this monotonous
increasing property can indicate an arrow of time in the universe evolution, though the quantum version of the arrow of time is still very puzzling. 相似文献
17.
In this work we consider the entropy-corrected version of interacting holographic dark energy (HDE), in the non-flat universe
enclosed by apparent horizon. Two corrections of entropy so-called logarithmic ‘LEC’ and power-law ‘PLEC’ in HDE model with
apparent horizon as an IR-cutoff are studied. The ratio of dark matter to dark energy densities u, equation of state parameter w
D
and deceleration parameter q are obtained. We show that the cosmic coincidence problem is solved for interacting models. By studying the effect of interaction
in EoS parameter of both models, we see that the phantom divide may be crossed and also understand that the interacting models
can drive an acceleration expansion at the present and future, while in non-interacting case, this expansion can happen only
at the early time. The graphs of deceleration parameter for interacting models, show that the present acceleration expansion
is preceded by a sufficiently long period deceleration at past. Moreover, the thermodynamical interpretation of interaction
between LECHDE and dark matter is described. We obtain a relation between the interaction term of dark components and thermal
fluctuation in a non-flat universe, bounded by the apparent horizon. In limiting case, for ordinary HDE, the relation of interaction
term versus thermal fluctuation is also calculated. 相似文献
18.
M. Malekjani A. Khodam-Mohammadi M. Taji 《International Journal of Theoretical Physics》2011,50(10):3112-3124
The polytropic gas model is investigated as an interacting dark energy scenario. The cosmological implications of the model
including the evolution of EoS parameter w
Λ, energy density ΩΛ and deceleration parameter q are investigated. We show that, depending on the parameter of model, the interacting polytropic gas can behave as a quintessence
or phantom dark energy. In this model, the phantom divide is crossed from below to up. The evolution of q in the context of polytropic gas dark energy model represents the decelerated phase at the early time and accelerated phase
later. The singularity of this model is also discussed. Eventually, we establish the correspondence between interacting polytropic
gas model with tachyon, K-essence and dilaton scalar fields. The potential and the dynamics of these scalar field models are
reconstructed according to the evolution of interacting polytropic gas. 相似文献
19.
Hassan Amirhashchi Anirudh Pradhan H. Zainuddin 《International Journal of Theoretical Physics》2011,50(11):3529-3543
We study the evolution of the dark energy parameter in a spatially homogeneous and isotropic FRW space-time filled with barotropic
fluid and dark energy by considering a time dependent deceleration parameter. Two cases are discussed when the dark energy
is minimally coupled to the perfect fluid as well as direct interaction with it. It is concluded that in both non-interacting
and interacting cases only open and flat universes cross the phantom region. We find that during the evolution of the universe,
the equation of state (EoS) for dark energy ω
D
changes from ω
D
>−1 to ω
D
<−1, which is consistent with recent observations. The cosmic jerk parameter in our derived models is also found to be in
good agreement with the recent data of astrophysical observations. 相似文献
20.
Anirudh Pradhan H. Amirhashchi Bijan Saha 《International Journal of Theoretical Physics》2011,50(9):2923-2938
A new dark energy model in anisotropic Bianchi type-I (B-I) space-time with time dependent equation of state (EoS) parameter
and constant deceleration parameter has been investigated in the present paper. The Einstein’s field equations have been solved
by applying a variation law for generalized Hubble’s parameter (Berman in Il Nuovo Cimento B 74:182, 1983) which generates two types of solutions, one is of power-law type and other is of the exponential form. The existing range
of the dark energy EoS parameter ω for derived model is found to be in good agreement with the three recent observations (i) SNe Ia data (Knop et al. in Astrophys.
J. 598:102, 2003), (ii) SNe Ia data collaborated with CMBR anisotropy and galaxy clustering statistics (Tegmark et al. in Astrophys. J. 606:702,
2004) and (iii) a combination of cosmological datasets coming from CMB anisotropies, luminosity distances of high redshift type
Ia supernovae and galaxy clustering (Hinshaw et al. in Astrophys. J. Suppl. Ser. 180:225, 2009 and Komatsu et al. in Astrophys. J. Suppl. Ser. 180:330, 2009). The cosmological constant Λ is found to be a decreasing function of time and it approaches a small positive value at the
present epoch which is corroborated by results from recent supernovae Ia observations. It has also been suggested that the
dark energy that explains the observed accelerating universe may arise due to the contribution to the vacuum energy of the
EoS in a time dependent background. Geometric and kinematic properties of the model and the behaviour of the anisotropy of
the dark energy have been carried out. 相似文献