53 research outputs found
Statefinder diagnosis in a non-flat universe and the holographic model of dark energy
In this paper, we study the holographic dark energy model in non-flat
universe from the statefinder viewpoint. We plot the evolutionary trajectories
of the holographic dark energy model for different values of the parameter
as well as for different contributions of spatial curvature, in the statefinder
parameter-planes. The statefinder diagrams characterize the properties of the
holographic dark energy and show the discrimination between this scenario and
other dark energy models. As we show, the contributions of the spatial
curvature in the model can be diagnosed out explicitly by the statefinder
diagrams. Furthermore, we also investigate the holographic dark energy model in
the plane, which can provide us with a useful dynamical diagnosis
complement to the statefinder geometrical diagnosis.Comment: 16 pages, 4 figures; final versio
Generalized Ricci dark energy in Horava-Lifshitz gravity
In this letter, we have considered generalized Ricci dark energy in the
Horava-Lifshitz gravity. We have reconstructed the Hubble's parameter in terms
of fractional densities. We have viewed the equation of state parameter in this
situation. Also, we have examined the behavior of deceleration parameter and
investigated the nature of the statefinder diagnostics. The equation of state
parameter has exhibited quintessence-like behavior and from the plot of the
deceleration parameter we have observed an ever accelerating universe
Statefinder Parameters for Interacting Phantom Energy with Dark Matter
We apply in this paper the statefinder parameters to the interacting phantom
energy with dark matter. There are two kinds of scaling solutions in this
model. It is found that the evolving trajectories of these two scaling
solutions in the statefinder parameter plane are quite different, and that are
also different from the statefinder diagnostic of other dark energy models.Comment: 9 pages, 12 figures, some references are added, some words are
modifie
Holographic dark energy with time varying parameter
We consider the holographic dark energy model in which the model parameter
evolves slowly with time. First we calculate the evolution of EoS
parameter as well as the deceleration parameter in this generalized version of
holographic dark energy (GHDE). Depending on the parameter , the phantom
regime can be achieved earlier or later compare with original version of
holographic dark energy. The evolution of energy density of GHDE model is
investigated in terms of parameter . We also show that the time-dependency
of can effect on the transition epoch from decelerated phase to
accelerated expansion. Finally, we perform the statefinder diagnostic for GHDE
model and show that the evolutionary trajectories of the model in plane
are strongly depend on the parameter .Comment: 16 pages, 4 figures, accepted by Astrophys Space Sc
Statefinder diagnostic and stability of modified gravity consistent with holographic and new agegraphic dark energy
Recently one of us derived the action of modified gravity consistent with the
holographic and new-agegraphic dark energy. In this paper, we investigate the
stability of the Lagrangians of the modified gravity as discussed in [M. R.
Setare, Int. J. Mod. Phys. D 17 (2008) 2219; M. R. Setare, Astrophys. Space
Sci. 326 (2010) 27]. We also calculate the statefinder parameters which
classify our dark energy model.Comment: 12 pages, 2 figures, accepted by Gen. Relativ. Gravi
Statefinder and Om Diagnostics for Interacting New Holographic Dark Energy Model and Generalized Second Law of Thermodynamics
In this work, we have considered that the flat FRW universe is filled with
the mixture of dark matter and the new holographic dark energy. If there is an
interaction, we have investigated the natures of deceleration parameter,
statefinder and diagnostics. We have examined the validity of the first
and generalized second laws of thermodynamics under these interactions on the
event as well as apparent horizon. It has been observed that the first law is
violated on the event horizon. However, the generalized second law is valid
throughout the evolution of the universe enveloped by the apparent horizon.
When the event horizon is considered as the enveloping horizon, the generalized
second law is found to break down excepting at late stage of the universe.Comment: 9 pages, 13 figure
Interacting Ricci Dark Energy with Logarithmic Correction
Motivated by the holographic principle, it has been suggested that the dark
energy density may be inversely proportional to the area 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 , the deceleration
parameter and 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.Comment: 24 pages, accepted for publication in 'Astrophysics and Space
Science, DOI:10.1007/s10509-012-1031-8
Reconstructing quintom from WMAP 5-year observations: Generalized ghost condensate
In the 5-year WMAP data analysis, a new parametrization form for dark energy
equation-of-state was used, and it has been shown that the equation-of-state,
, crosses the cosmological-constant boundary . Based on this
observation, in this paper, we investigate the reconstruction of quintom dark
energy model. As a single-real-scalar-field model of dark energy, the
generalized ghost condensate model provides us with a successful mechanism for
realizing the quintom-like behavior. Therefore, we reconstruct this
scalar-field quintom dark energy model from the WMAP 5-year observational
results. As a comparison, we also discuss the quintom reconstruction based on
other specific dark energy ansatzs, such as the CPL parametrization and the
holographic dark energy scenarios.Comment: 8 pages, 11 figure
Natural Phantom Dark Energy, Wiggling Hubble Parameter and Direct Data
Recent direct data indicate that the parameter may wiggle with
respect to . On the other hand the luminosity distance data of supernovae
flatten the wiggles of because of integration effect. It is expected
that the fitting results can be very different in a model permitting a wiggling
because the data of supernovae is highly degenerated to such a model. As
an example the natural phantom dark energy is investigated in this paper. The
dynamical property of this model is studied. The model is fitted by the direct
data set and the SNLS data set, respectively. And the results are quite
different, as expected. The quantum stability of this model is also shortly
discussed. We find it is a viable model if we treat it as an effective theory
truncated by an upperbound.Comment: 14 pages, 2 figures, discussions on the stability added, conclusions
not change
Cosmological evolution and statefinder diagnostic for new holographic dark energy model in non flat universe
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 and in
this model are derived and the evolutionary trajectories in 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 and
planes for best fit values of the parameters of new HDE model.Comment: 11 pages, 5 figures, Accepted by Astrophys. Space Sc
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