Holographic dark energy in a vector field cosmology

2015 ◽  
Vol 12 (10) ◽  
pp. 1550119 ◽  
Author(s):  
S. Davood Sadatian
Keyword(s):  
Dark Energy ◽  
Vector Field ◽  
Equation Of State ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Lorentz Invariance ◽  
Holographic Model ◽  
Dark Energy Density ◽  
Invariance Violation ◽  
Lorentz Invariance Violation

We obtain interacting holographic dark energy density in the framework of vector field cosmology (LIV). We consider possible modification of equation of state for the holographic energy density in lorentz invariance violation cosmology. In this case we select Jeans length as the IR cut-off in the holographic model. Then we consider the interaction between holographic energy densities ρΛ and ρm in this framework.

scholarly journals INTERACTING NON-MINIMALLY COUPLED CANONICAL, PHANTOM AND QUINTOM MODELS OF HOLOGRAPHIC DARK ENERGY IN NON-FLAT UNIVERSE

2010 ◽  
Vol 19 (12) ◽  
pp. 1987-2002 ◽  
Author(s):  
M. R. SETARE ◽  
ALBERTO ROZAS-FERNÁNDEZ
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Recent Work ◽  
Event Horizon ◽  
Holographic Dark Energy ◽  
Closed Universe ◽  
Holographic Model ◽  
Interacting Dark Energy ◽  
Flat Universe

Motivated by our recent work,72 we generalize this work to the interacting non-flat case. Therefore in this paper we deal with canonical, phantom and quintom models, with various fields that are non-minimally coupled to gravity, within the framework of interacting holographic dark energy. We employ the holographic model of interacting dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L.

The role of anisotropy in holographic modified gravity

2014 ◽  
Vol 92 (5) ◽  
pp. 370-374
Author(s):  
V. Fayaz ◽  
H. Hossienkhani ◽  
M. Amirabadi ◽  
A. Aghamohammadi
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
Holographic Dark Energy ◽  
Holographic Model ◽  
Holographic Dark Energy Model ◽  
Cosmological Implication ◽  
Reconstruction Scheme

In this paper, we study a cosmological implication of holographic dark energy in modified gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in a nonisotropic universe. The purpose of this work is to develop a reconstruction scheme for the modified gravity with f(R) action using the holographic energy density. Hence one can generate a phantom-like equation of state from a holographic dark energy model in a nonisotropic universe in the modified gravity cosmology framework.

scholarly journals HOLOGRAPHIC MODIFIED GRAVITY

2008 ◽  
Vol 17 (12) ◽  
pp. 2219-2228 ◽  
Author(s):  
M. R. SETARE
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Modified Gravity ◽  
Holographic Dark Energy ◽  
Holographic Dark Energy Model ◽  
Dark Energy Density ◽  
Reconstruction Scheme ◽  
Flat Universe ◽  
Cosmological Application

In this paper, we investigate cosmological application of holographic dark energy density in the modified gravity framework. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in a spatially flat universe. Our calculation shows that, taking ΩΛ = 0.73 for the present time, it is possible to have wΛ crossing -1. This implies that one can generate a phantom-like equation of state from a holographic dark energy model in flat universe in the modified gravity cosmology framework. Also, we develop a reconstruction scheme for the modified gravity with f(R) action.

scholarly journals SECOND-ORDER INVARIANTS AND HOLOGRAPHY

2012 ◽  
Vol 21 (12) ◽  
pp. 1250091 ◽  
Author(s):  
ORLANDO LUONGO ◽  
LUCA BONANNO ◽  
GERARDO IANNONE
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Holographic Dark Energy ◽  
Statistical Tests ◽  
A Priori ◽  
Second Order ◽  
Fine Tuning ◽  
Dark Energy Density ◽  
Event Horizons

Motivated by recent works on the role of the holographic principle in cosmology, we relate a class of second-order Ricci invariants to the IR cutoff characterizing the holographic dark energy density. The choice of second-order invariants provides an invariant way to account the problem of causality for the correct cosmological cutoff, since the presence of event horizons is not an a priori assumption. We find that these models work fairly well, by fitting the observational data, through a combined cosmological test with the use of SNeIa, BAO and CMB. This class of models is also able to overcome the fine-tuning and coincidence problems. Finally, to make a comparison with other recent models, we adopt the statistical tests AIC and BIC.

scholarly journals HOLOGRAPHIC DARK ENERGY MODEL CHARACTERIZED BY THE CONFORMAL-AGE-LIKE LENGTH

2012 ◽  
Vol 27 (16) ◽  
pp. 1250085 ◽  
Author(s):  
ZHUO-PENG HUANG ◽  
YUE-LIANG WU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Dimensional Space ◽  
Early Time ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
Frw Universe

A holographic dark energy model characterized by the conformal-age-like length scale [Formula: see text] is motivated from the four-dimensional space–time volume at cosmic time t in the flat Friedmann–Robertson–Walker (FRW) universe. It is shown that when the background constituent with constant equation of state wm dominates the universe in the early time, the fractional energy density of the dark energy scales as [Formula: see text] with the equation of state given by [Formula: see text]. The value of wm is taken to be wm≃-1 during inflation, wm = ⅓ in radiation-dominated epoch and wm = 0 in matter-dominated epoch, respectively. When the model parameter d takes the normal value at order one, the fractional density of dark energy is naturally negligible in the early universe, Ω de ≪1 at a ≪1. With such an analytic feature, the model can be regarded as a single-parameter model like the ΛCDM model, so that the present fractional energy density Ω de (a = 1) can solely be determined by solving the differential equation of Ωde once d is given. We further extend the model to the general case in which both matter and radiation are present. The scenario involving possible interaction between the dark energy and the background constituent is also discussed.

scholarly journals COSMOLOGICAL CONSTRAINT AND ANALYSIS ON HOLOGRAPHIC DARK ENERGY MODEL CHARACTERIZED BY THE CONFORMAL-AGE-LIKE LENGTH

2012 ◽  
Vol 27 (22) ◽  
pp. 1250130 ◽  
Author(s):  
ZHUO-PENG HUANG ◽  
YUE-LIANG WU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Energy Model ◽  
Single Parameter ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Holographic Dark Energy Model ◽  
Λcdm Model

We present a best-fit analysis on the single-parameter holographic dark energy model characterized by the conformal-age-like length, [Formula: see text]. Based on the Union2 compilation of 557 supernova Ia (SNIa) data, the baryon acoustic oscillation (BAO) results from the Sloan Digital Sky Survey data release 7 (SDSS DR7) and the cosmic microwave background radiation (CMB) data from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7), we show that the model gives the minimal [Formula: see text], which is comparable to [Formula: see text] for the ΛCDM model. The single parameter d concerned in the model is found to be d = 0.232±0.006±0.009. Since the fractional density of dark energy Ωde~ d2a2at a ≪ 1, the fraction of dark energy is naturally negligible in the early universe, Ωde≪ 1 at a ≪ 1. The resulting constraints on the present fractional energy density of matter and the equation of state are [Formula: see text] and [Formula: see text] respectively. We also provide a systematic analysis on the cosmic evolutions of the fractional energy density of dark energy, the equation of state of dark energy, the deceleration parameter and the statefinder. It is noticed that the equation of state crosses from wde> -1 to wde< -1, the universe transits from decelerated expansion (q > 0) to accelerated expansion (q < 0) recently, and the statefinder may serve as a sensitive diagnostic to distinguish the CHDE model with the ΛCDM model.

scholarly journals DARK ENERGY IN GLOBAL BRANE UNIVERSE

2007 ◽  
Vol 16 (10) ◽  
pp. 1633-1640 ◽  
Author(s):  
YONGLI PING ◽  
LIXIN XU ◽  
CHENGWU ZHANG ◽  
HONGYA LIU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Exact Solutions ◽  
Deceleration Parameter ◽  
Mass Density ◽  
Density Parameter ◽  
Dark Energy Density ◽  
Friedmann Equations

We discuss the exact solutions of brane universes and the results indicate that the Friedmann equations on the branes are modified with a new density term. Then, we assume the new term as the density of dark energy. Using Wetterich's parametrization equation of state (EOS) of dark energy, we obtain that the new term varies with the redshift z. Finally, the evolutions of the mass density parameter Ω2, dark energy density parameter Ωx and deceleration parameter q2 are studied.

scholarly journals Tsallis holographic model of dark energy: Cosmic behavior, statefinder analysis and ωD–ωD′ pair in the nonflat universe

2019 ◽  
Vol 28 (15) ◽  
pp. 1950164 ◽  
Author(s):  
Vipin Chandra Dubey ◽  
Umesh Kumar Sharma ◽  
A. Beesham
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Deceleration Parameter ◽  
Holographic Dark Energy ◽  
Apparent Horizon ◽  
Density Parameter ◽  
Holographic Model ◽  
Spatial Curvature ◽  
Present Value ◽  
Evolutionary Trajectories

This paper investigates the Tsallis holographic dark energy (THDE) model in accordance with the apparent horizon as an infrared cut-off, in a non flat universe. The cosmological evolution of the deceleration parameter and equation of state of THDE model are calculated. The evolutionary trajectories are plotted for the THDE model for distinct values of the Tsallis parameter [Formula: see text] besides distinct spatial curvature contributions, in the statefinder [Formula: see text] parameter-pairs and [Formula: see text] plane, considering the present value of dark energy (DE) density parameter [Formula: see text], [Formula: see text], in the light of [Formula: see text] observational data. The statefinder and [Formula: see text] plane plots specify the feature of the THDE and demonstrate the separation between this framework and other models of DE.

scholarly journals GRAVITATIONAL LENSING STATISTICS AS A PROBE OF DARK ENERGY

2000 ◽  
Vol 15 (16) ◽  
pp. 1023-1029 ◽  
Author(s):  
ZONG-HONG ZHU
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Cosmological Model ◽  
Gravitational Lensing ◽  
Mass Density ◽  
Density Parameter ◽  
Dark Energy Density ◽  
Analytic Expression ◽  
Cosmic Mass

By using the comoving distance, we derive an analytic expression for the optical depth of gravitational lensing, which depends on the redshift to the source and the cosmological model characterized by the cosmic mass density parameter Ωm, the dark energy density parameter Ωm and its equation of state ωx = px/ρx. It is shown that, the larger the dark energy density and the more negative its pressure, the higher is the gravitational lensing probability. This fact can provide an independent constraint for dark energy.

INTERACTING MODIFIED HOLOGRAPHIC DARK ENERGY IN A NONFLAT UNIVERSE

2011 ◽  
Vol 20 (03) ◽  
pp. 269-279 ◽  
Author(s):  
M. R. SETARE ◽  
A. BANIJAMALI ◽  
B. FAZLPOUR
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Energy Density ◽  
Event Horizon ◽  
Necessary Conditions ◽  
Holographic Dark Energy ◽  
Nucl Phys ◽  
Consistent Model

In this paper, we extend the modified holographic dark energy proposed by Wei [H. Wei, Nucl. Phys. B819 (2009) 210] to the interacting case and in a nonflat universe. We first choose the IR cutoff to be the radius of the event horizon Rh measured on the sphere of the horizon and derive the equation of state for the holographic energy density in the nonflat universe. Then, by choosing the Jeans length as the IR cutoff, we obtain the necessary conditions for having a cosmologically consistent model.

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