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1.
In view of the recent observation data indicating that the equation of state of the dark energy might be smaller than −1, this leads to introduction of phantom models featured by their negative kinetic energy to account for the regime of equation of state w < −1. In this paper, we discuss the possibility of using a nonminimally coupled complex scalar field as phantom to realize the equation-of-state parameter w < −1. The main equations which govern the evolution of the universe are obtained. The relations between the potential of the field and red-shift, namely, the reconstruction equations are derived.
PACS 04.40.-b, 98.80.Cq, 98.80.Hw 相似文献
2.
Yunshuang Du Hongsheng Zhang Xin-Zhou Li 《The European Physical Journal C - Particles and Fields》2011,71(6):1660
Recently, type Ia supernova data appear to support a dark energy whose equation of state w crosses −1, which is a much more amazing problem than the acceleration of the universe. We show that it is possible for the
equation of state to cross the phantom divide by a scalar field in gravity with an additional inverse power-law term of the
Ricci scalar in the Lagrangian. The necessary and sufficient condition for a universe in which the dark energy can cross the
phantom divide is obtained. Some analytical solutions with w<−1 or w>−1 are obtained. A minimally coupled scalar with different potentials, including quadratic, cubic, quantic, exponential and
logarithmic potentials are investigated via numerical methods, respectively. All these potentials lead to the crossing behavior.
We show that it is a robust result which is hardly dependent on the concrete form of the potential of the scalar. 相似文献
3.
We analyze an oscillating universe model in brane world cenario. The oscillating universe cycles through a series of expansions
and contractions and its energy density is dominated by dust matter at early-time expansion phase and by phantom dark energy
at late-time expansion phase. We find that the period of the oscillating universe is not sensitive to the tension of the brane,
but sensitive to the equation-of-state parameter w of the phantom dark energy, and the ratio of the period to the current Hubble age approximately varies from 3 to 9 when the
parameter w changes from −1.4 to −1.1. The fraction of time that the oscillating universe spends in the coincidence state is also comparable
to the period of the oscillating universe. This result indicates that the coincidence problem can be significantly ameliorated
in the oscillating universe without singularity. 相似文献
4.
M.R. Setare 《The European Physical Journal C - Particles and Fields》2007,52(3):689-692
We employ the generalized Chaplygin gas of interacting dark energy to obtain the equation of state for the generalized Chaplygin
gas energy density in a non-flat universe. By choosing a negative value for B we see that wΛ
eff<-1, which corresponds to a universe dominated by phantom dark energy. 相似文献
5.
We investigate the modified Chaplygin gas (MCG) with interaction between holographic dark energy proposed by Li and dark matter. In this model, evolution of the universe is described in detail, which is from deceleration to acceleration. Specifically, the evolutions of related cosmological quantities such as density parameter, the equation of state of holographic dark energy, deceleration parameter and transition redshift are discussed. Moreover, we also give their present values which are consistent with the lately observations. Furthermore, the results given by us show such a model can accommodate a transition of the dark energy from a normal state wx 〉 -1 to ωx 〈 -1 phantom regimes. 相似文献
6.
Esmaeil Ebrahimi Ahmad Sheykhi Hamzeh Alavirad 《Central European Journal of Physics》2013,11(7):949-960
We investigate the generalized Quantum Chromodynamics (QCD) ghost model of dark energy in the framework of Einstein gravity. First, we study the non-interacting generalized ghost dark energy in a flat Friedmann-Robertson-Walker (FRW) background. We obtain the equation of state parameter, w D = p/ρ, the deceleration parameter, and the evolution equation of the generalized ghost dark energy. We find that, in this case, w D cannot cross the phantom line (w D > ?1) and eventually the universe approaches a de-Sitter phase of expansion (w D → ?1). Then, we extend the study to the interacting ghost dark energy in both a flat and non-flat FRW universe. We find that the equation of state parameter of the interacting generalized ghost dark energy can cross the phantom line (w D < ?1) provided the parameters of the model are chosen suitably. Finally, we constrain the model parameters by using the Markov Chain Monte Carlo (MCMC) method and a combined dataset of SNIa, CMB, BAO and X-ray gas mass fraction. 相似文献
7.
We investigate the QCD ghost model of dark energy in the framework of RS II braneworld. We assume there is an energy flow between the brane and bulk, and hence the continuity equation for the ghost dark energy is violated, while it is still preserved for the dark matter on the brane. We find that with the brane-bulk interaction, the equation of state parameter of ghost dark energy on the brane, can cross the phantom line w D =?1 at the present time, which confirms by some cosmological evidences. This result is in contrast to the standard cosmology where w D of ghost dark energy never cross the phantom line and the universe enters a de Sitter phase at the late time. 相似文献
8.
Recent observations of the Cosmic Microwave Background, Supernovae and Sloan Digital Sky Survey (SDSS) show that our universe has a critical energy density, and roughly 2/3 of it is dark energy, which drives the accelerating expansion of the cosmos. In view of the astrophysical data, we find that the equation of state parameter of the dark energy lies in a narrow range around w = −1. In this paper, we construct a cosmology model with a Rarita-Schwinger field to realize the equation of state parameter w < −1 or w > −1 and discuss its stability. 相似文献
9.
Jianbo Lu Yuting Wang Yabo Wu Tianqiang Wang 《The European Physical Journal C - Particles and Fields》2011,71(11):1800
We use the Markov Chain Monte Carlo method to investigate global constraints on the generalized holographic (GH) dark energy
with flat and non-flat universe from the current observed data: the Union2 dataset of type supernovae Ia (SNIa), high-redshift
Gamma-Ray Bursts (GRBs), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation
(BAO), and the cosmic microwave background (CMB) data. The most stringent constraints on the GH model parameter are obtained.
In addition, it is found that the equation of state for this generalized holographic dark energy can cross over the phantom
boundary w
de
=−1. 相似文献
10.
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
11.
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
12.
Theerakarn Phetnora Roongtum Sooksan Burin Gumjudpai 《General Relativity and Gravitation》2010,42(2):225-240
We describe non-flat standard Friedmann cosmology of canonical scalar field with barotropic fluid in form of non-linear Schrödinger-type (NLS) formulation in which all cosmological dynamical quantities are expressed in term of Schrödinger quantities as similar to those in time-independent quantum mechanics. We assume the expansion to be superfast, i.e. phantom expansion. We report all Schrödinger-analogous quantities to scalar field cosmology. Effective equation of state coefficient is analyzed and illustrated. We show that in a non-flat universe, there is no fixed w eff value for the phantom divide. In a non-flat universe, even w eff > ?1, the expansion can be phantom. Moreover, in open universe, phantom expansion can happen even with w eff > 0. We also report scalar field exact solutions within frameworks of the Friedmann formulation and the NLS formulation in non-flat universe cases. 相似文献
13.
Rong-Jia Yang Jing-Zhao Qi Lihua Feng 《International Journal of Theoretical Physics》2012,51(6):1692-1697
Assuming that the equation of state of dark energy is a constant, we obtain the allowed interval of the equation of state
of dark energy: w
D≥−1, bounded from the generalized second law of thermodynamics, in a universe enveloped by the apparent horizon and containing
a Schwarzschild black hole. 相似文献
14.
We investigate the QCD ghost model of dark energy in the framework of Brans-Dicke cosmology. First, we study the non-interacting ghost dark energy in a flat Brans-Dicke theory. In this case we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of ghost energy density. Interestingly enough, we find that the equation of state parameter of the non-interacting ghost dark energy can cross the phantom line (wD=−1) provided the parameters of the model are chosen suitably. Then, we generalize the study to the interacting ghost dark energy in both flat and non-flat Brans-Dicke framework and find out that the transition of wD to phantom regime can be more easily achieved for than when resort to the Einstein field equations is made. 相似文献
15.
Singularities in the dark energy universe are discussed, assuming that there is a bulk viscosity in the cosmic fluid. In particular,
it is shown how the physically natural assumption of letting the bulk viscosity be proportional to the scalar expansion in
a spatially flat FRW universe can drive the fluid into the phantom region (w < −1), even if it lies in the quintessence region (w > −1) in the non-viscous case. 相似文献
16.
K. Karami S. Ghaffari J. Fehri 《The European Physical Journal C - Particles and Fields》2009,64(1):85-88
By introducing the polytropic gas model of interacting dark energy, we obtain the equation of state for the polytropic gas
energy density in a non-flat universe. We show that for an even polytropic index by choosing
$K>Ba^{\frac{3}{n}}$K>Ba^{\frac{3}{n}}
, one can obtain ω
Λ
eff<−1, which corresponds to a universe dominated by phantom dark energy. 相似文献
17.
We study the phantom inflation in little rip cosmology, in which the current acceleration is driven by the field with the parameter of state w<−1, but since w tends to −1 asymptotically, the rip singularity occurs only at infinite time. In this scenario, before the rip singularity is arrived, the universe is in an inflationary regime. We numerically calculate the spectrum of primordial perturbation generated during this period and find that the results may be consistent with observations. This implies that if the reheating happens again, the current acceleration might be just a start of phantom inflation responsible for the upcoming observational universe. 相似文献
18.
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
19.
A new dark energy model called “ghost dark energy” was recently suggested to explain the observed accelerating expansion of
the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter,
ρ
D
= α H, where α is a constant of order LQCD3{\Lambda_{\rm QCD}^3} and ΛQCD ~ 100 MeV is QCD mass scale. In this Letter, we extend the ghost dark energy model to the universe with spatial curvature
in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail.
In the absence of interaction the equation of state parameter of ghost dark energy is always w
D
> −1 and mimics a cosmological constant in the late time, while it is possible to have w
D
< −1 provided the interaction is taken into account. When k = 0, all previous results of ghost dark energy in flat universe are recovered. For the observational test, we use Supernova
type Ia Gold sample, shift parameter of cosmic microwave background radiation and the correlation of acoustic oscillation
on the last scattering surface and the baryonic acoustic peak from Sloan Digital Sky Survey are used to confine the value
of free parameter of mentioned model. 相似文献
20.
We propose a phantom crossing Dvali–Gabadadze–Porrati (DGP) model. In our model, the effective equation of state of the DGP
gravity crosses the phantom divide line. We demonstrate crossing of the phantom divide does not occur within the framework
of the original DGP model or the DGP model developed by Dvali and Turner. By extending their model, we construct a model that
realizes crossing of the phantom divide. We find that the smaller the value of the new introduced parameter β is, the older epoch crossing of the phantom divide occurs in. Our model can account for late-time acceleration of the universe
without dark energy. We investigate and show the property of Phantom crossing DGP model. 相似文献