共查询到20条相似文献，搜索用时 0 毫秒
1.
Mohammad Malekjani 《Astrophysics and Space Science》2013,347(2):405-410
We generalize the holographic dark energy model described in Hubble length IR cutoff by assuming a slowly time varying function for holographic parameter c 2. We calculate the evolution of EoS parameter and the deceleration parameter as well as the evolution of dark energy density parameter of the model in flat FRW universe. We show that in this model the phantom line is crossed from quintessence regime to phantom regime which is in agreement with observation. The evolution of deceleration parameter of the model indicates the transition from decelerated to accelerated expansion consistently with observation. Eventually, we show that the holographic dark energy model with Hubble horizon IR cutoff can interpret the pressureless dark matter era at the early time and dark energy dominated phase later. The singularity of the model is also calculated. 相似文献
2.
The interaction of modified holographic dark energy and dark matter with varying G in flat Kaluza Klein universe is considered. Further, we take infrared cutoff scale L as future event horizon. In this scenario, equations of state parameter as well as evolution are explored. We also check
the validity of the generalized second law of thermodynamics. It is interesting to mention here that our results show consistency
with the present observations. 相似文献
3.
Antonio Pasqua A. Khodam-Mohammadi Mubasher Jamil R. Myrzakulov 《Astrophysics and Space Science》2012,340(1):199-208
Motivated by the holographic principle, it has been suggested that the dark energy density may be inversely proportional to the area A of the event horizon of the universe. However, such a model would have a causality problem. In this work, we consider the entropy-corrected version of the holographic dark energy model in the non-flat FRW universe and we propose to replace the future event horizon area with the inverse of the Ricci scalar curvature. We obtain the equation of state (EoS) parameter ω Λ, the deceleration parameter q and WD￠\Omega_{D}' in the presence of interaction between Dark Energy (DE) and Dark Matter (DM). Moreover, we reconstruct the potential and the dynamics of the tachyon, K-essence, dilaton and quintessence scalar field models according to the evolutionary behavior of the interacting entropy-corrected holographic dark energy model. 相似文献
4.
Here we consider our universe as homogeneous spherically symmetric FRW model and analyze the thermodynamics of this model
of the universe in scalar-tensor theory. Assuming the first law of thermodynamics validity of the generalized second law of
thermodynamics (GSLT) at the event horizon is examined in both the cases when the universe is filled with perfect fluid and
the holographic dark energy. 相似文献
5.
A. Aghamohammadi 《Astrophysics and Space Science》2014,352(1):1-5
We try to study the corresponding relation between f(T) gravity and holographic dark energy (HDE). A kind of energy density from f(T) is introduced which has the same role as HDE density. A f(T) model according to the HDE model is calculated. We find out a torsion scalar T based on the scalar factor is assumed by Capoziello et al. (Phys. Lett. B 639:135, 2006). The effective torsion equation of state, deceleration parameter of the holographic f(T)-gravity model are calculated. 相似文献
6.
We propose in this paper an interacting holographic dark energy (IHDE) model in chameleon–tachyon cosmology by interaction
between the components of the dark sectors. In the formalism, the interaction term emerges from the scalar field coupling
matter Lagrangian in the model rather than being inserted into the formalism as an external source for the interaction. The
correspondence between the tachyon field and the holographic dark energy (HDE) densities allows to reconstruct the tachyon
scalar field and its potential in a flat FRW universe. The model can show the accelerated expansion of the universe and satisfies
the observational data. 相似文献
7.
The aim of this paper is to study new holographic dark energy (HDE) model in modified \(f(R,T)\) gravity theory within the framework of a flat Friedmann-Robertson-Walker model with bulk viscous matter content. It is thought that the negative pressure caused by the bulk viscosity can play the role of dark energy component, and drive the accelerating expansion of the universe. This is the motive of this paper to observe such phenomena with bulk viscosity. In the specific model \(f(R,T)=R+\lambda T\), where \(R\) is the Ricci scalar, \(T\) the trace of the energy-momentum tensor and \(\lambda \) is a constant, we find the solution for non-viscous and viscous new HDE models. We analyze new HDE model with constant bulk viscosity, \(\zeta =\zeta _{0}= \text{const.}\) to explain the present accelerated expansion of the universe. We classify all possible scenarios (deceleration, acceleration and their transition) with possible positive and negative ranges of \(\lambda \) over the constraint on \(\zeta _{0}\) to analyze the evolution of the universe. We obtain the solutions of scale factor and deceleration parameter, and discuss the evolution of the universe. We observe the future finite-time singularities of type I and III at a finite time under certain constraints on \(\lambda \). We also investigate the statefinder and \(\mathit{Om}\) diagnostics of the viscous new HDE model to discriminate with other existing dark energy models. In late time the viscous new HDE model approaches to \(\varLambda \mathit{CDM}\) model. We also discuss the thermodynamics and entropy of the model and find that it satisfies the second law of thermodynamics. 相似文献
8.
9.
Ritabrata Biswas Nairwita Mazumder Subenoy Chakraborty 《Astrophysics and Space Science》2011,335(2):603-609
In this paper we deal with accretion of dark energy in the holographic dark energy model for a general non-rotating static
spherically symmetric black hole. The mass of the black hole increases or decreases depending on the nature of the holographic
dark energy (quintessence or phantom) as well as on some integration parameters. It is to be illustrated that the enhancement
or reduction of mass of a black hole is independent of the mass or size of the black hole itself. Rather it depends only upon
the radius of the event horizon of the universe. Finally, the generalized second law of thermodynamics has been studied on
the event horizon to be assured that the law holds even if when the black hole mass is decreasing though it is engrossing
some mass. 相似文献
10.
Antonio Pasqua 《Astrophysics and Space Science》2013,346(2):531-543
In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). I propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature R. I obtain the equation of state (EoS) parameter ω Λ , the deceleration parameter q and the evolution of energy density parameter $\varOmega_{D}'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results. 相似文献
11.
Kazuharu Bamba Mubasher Jamil D. Momeni Ratbay Myrzakulov 《Astrophysics and Space Science》2013,344(1):259-267
We study the generalized second law (GSL) of thermodynamics in f(T) cosmology, where T is the torsion scalar in teleparallelism. We consider the universe as a closed bounded system filled with n component fluids in the thermal equilibrium with the cosmological boundary. We use two different cosmic horizons: the future event horizon and the apparent horizon. We show the conditions under which the GSL will be valid in specific scenarios of the quintessence and the phantom energy dominated eras. Further we associate two different entropies with the cosmological horizons: with a logarithmic correction term and a power-law correction term. We also find the conditions for the GSL to be satisfied or violated by imposing constraints on model parameters. 相似文献
12.
13.
H. Farajollahi A. Ravanpak H. Shojaie M. Abolghasemi 《Astrophysics and Space Science》2014,350(1):325-331
This work is to study the generalized second law (GSL) of thermodynamics in tachyon cosmology where the tachyon field is coupled to the matter Lagrangian while the boundary of universe is assumed to be a dynamical apparent horizon. The two logarithmic and power law corrected entropy on the apparent horizon is also discussed and the conditions for validity of GSL in both scenarios are investigated by using observational data of Sne Ia. In comparison to other research works, since the model is constrained by observational data, the conditions obtained for the dimensionless constant parameter, α in both logarithmic and power law entropy correction of GSL are (physically) meaningful and realistic. The model also predicts an accelerating universe with no phantom crossing in the past or future. 相似文献
14.
M. Malekjani A. Khodam-Mohammadi N. Nazari-pooya 《Astrophysics and Space Science》2011,332(2):515-524
In this paper, the holographic dark energy model with new infrared cut-off proposed by Granda and Oliveros has been investigated
in spatially non flat universe. The dependency of the evolution of equation of state, deceleration parameter and cosmological
evolution of Hubble parameter on the parameters of new HDE model are calculated. Also, the statefinder parameters r and s in this model are derived and the evolutionary trajectories in s−r plane are plotted. We show that the evolutionary trajectories are dependent on the model parameters of new HDE model. Eventually,
in the light of SNe + BAO + OHD + CMB observational data, we plot the evolutionary trajectories in s−r and q−r planes for best fit values of the parameters of new HDE model. 相似文献
15.
Abdul Jawad Antonio Pasqua Surajit Chattopadhyay 《Astrophysics and Space Science》2013,344(2):489-494
In this paper, we discuss cosmological application of holographic Dark Energy (HDE) in the framework of f(G) modified gravity. For this purpose, we construct f(G) model with the inclusion of HDE and a well-known power law form of the scale factor a(t). The reconstructed f(G) is found to satisfy a sufficient condition for a realistic modified gravity model. We find quintessence behavior of effective equation of state (EoS) parameter ω DE through energy conditions in this context. Moreover, we observe that the squared speed of sound $v_{s}^{2}$ remains negative, which indicates the instability of HDE f(G) model. 相似文献
16.
Sanjay Sarkar 《Astrophysics and Space Science》2014,351(1):361-369
The present work deals with a spatially homogeneous and anisotropic Kantowski-Sachs space time filled with two minimally interacting fluids; dark matter and a hypothetical anisotropic fluid as the holographic dark energy components. To obtain an exact solution of the Einstein’s field equations, we used the assumption of linearly varying deceleration parameter. We have investigated geometric and kinematic properties of the model and the role of the anisotropic holographic dark energy in the evolution of the Kantowski-Sachs universe. Under the suitable condition, it is observed that the anisotropy parameter of the universe and the skewness parameter of the holographic dark energy approaches to zero for large cosmic time and the universe can achieve flatness for some particular moments throughout its entire lifetime. Results show that the coincidence parameter $( \Re= \frac{\rho_{\varLambda}}{\rho_{M}} )$ increases with increasing time and a big rip type future singularity will occur for this model. We have also applied the statefinder diagnostics method to study the behavior of different stages of the universe and to differentiate the proposed dark energy model from the ΛCDM model. Since in this model, the universe has a finite life time and passes through a significant time when the dark energy and the matter energy densities are roughly comparable, so considering $\frac{1}{ \Re_{0}} <\Re < \Re_{0}$ , where ?0 is any fixed ratio, we have calculated the fraction of total life time of the universe when the universe passes through the coincidental stage for this future singularity. The results are found to be consistent with recent cosmological observations. 相似文献
17.
18.
Among different candidates to play the role of Dark Energy (DE), modified gravity has emerged as offering a possible unification of Dark Matter (DM) and DE. The purpose of this work is to develop a reconstruction scheme for the modified gravity with f(T) action using holographic energy density. In the framework of the said modified gravity we have considered the equation of state of the Holographic DE (HDE) density. Subsequently we have developed a reconstruction scheme for modified gravity with f(T) action. Finally we have obtained a modified gravity action consistent with the HDE scenario. 相似文献
19.
We constrain holographic dark energy (HDE) with time varying gravitational coupling constant in the framework of the modified Friedmann equations using cosmological data from type Ia supernovae, baryon acoustic oscillations, cosmic microwave background radiation and X-ray gas mass fraction. Applying a Markov Chain Monte Carlo (MCMC) simulation, we obtain the best fit values of the model and cosmological parameters within 1σ confidence level (CL) in a flat universe as: $\varOmega_{b}h^{2}=0.0222^{+0.0018}_{-0.0013}$ , $\varOmega_{c}h^{2}=0.1121^{+0.0110}_{-0.0079}$ , $\alpha_{G}\equiv \dot{G}/(HG) =0.1647^{+0.3547}_{-0.2971}$ and the HDE constant $c=0.9322^{+0.4569}_{-0.5447}$ . Using the best fit values, the equation of state of the dark component at the present time w d0 at 1σ CL can cross the phantom boundary w=?1. 相似文献
20.
V. Fayaz H. Hossienkhani A. Farmany M. Amirabadi N. Azimi 《Astrophysics and Space Science》2014,351(1):299-306
It is shown that the acceleration of the universe can be understood by considering a f(T) gravity models. Modified teleparallel gravity theory with the torsion scalar has recently gained a lot of attention as a possible explanation of dark energy. For these f(T) gravity models, a variant of the accelerating cosmology reconstruction program is developed. We consider spatially homogenous and anisotropic Bianchi type I universe in the context of f(T) gravity. The de Sitter, power-law and general exponential solutions are assumed for the scale factor in each spatial direction and the corresponding cosmological models are reconstructed. We reconstruct f(T) theories from two different holographic dark energy models in different time durations. For the holographic dark energy model, the dark energy dominated era with new setting up is chosen for reconstruction, and the Ricci dark energy model, radiation, matter and dark energy dominated time durations are all investigated. Finally we have obtained a modified gravity action consistent with the holographic dark energy scenario. 相似文献