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 An interacting new holographic dark energy model: Observational constraints

2019 ◽  
Vol 28 (12) ◽  
pp. 1950152 ◽  
Author(s):  
Ehsan Sadri ◽  
Martiros Khurshudyan
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Observational Data ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Current Model ◽  
Energy Model ◽  
Late Time ◽  
Holographic Dark Energy Model ◽  
Frw Universe

In this paper, we study an interacting new holographic dark energy model (NHDE) in DGP braneworld with a spatially flat FRW universe. Mainly, in this study we concentrate our attention on both interacting and noninteracting forms of the model. The study shows that the equation of state and the deceleration parameter depict an accelerated universe for all variety of interactions. On the other hand, the StateFinder analysis shows that the interacting and noninteracting behave similar to both quintessence and phantom dark energy and for the present value obey the behavior of quintessence. Moreover, the result of [Formula: see text]-diagnostic emphasizes on the result of the equation of state showing that the current model in high–[Formula: see text] stays in the quintessence era and in the late time has the Phantom-like behavior. By the use of the squared sound speed [Formula: see text] we find that the present mode has a good stability. In order to obtain the best fit values of the parameters in this work, we used the latest observational data (Pantheon, Boss DR12 and Planck 2015) implementing MCMC method by the use of EMCEE python package. We also employ AkaikeInformation Criterion (AIC) and Bayesian Information Criterion (BIC) model selection tools and comparethe model with both [Formula: see text]CDM and holographic Ricci dark energy as the reference models. We observe that the evidence against the interacting and noninteracting NHDE with consideration of both references is strongly positive and BIC rules out the NHDE model. Generally, the results of AIC and BIC state that the observational data do not favor the NHDE model.

scholarly journals A TRACKER SOLUTION FOR A HOLOGRAPHIC DARK ENERGY MODEL

2006 ◽  
Vol 15 (06) ◽  
pp. 869-877 ◽  
Author(s):  
HUI LI ◽  
ZONG-KUAN GUO ◽  
YUAN-ZHONG ZHANG
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Dark Energy Model ◽  
Holographic Dark Energy ◽  
Cosmological Parameters ◽  
Energy Model ◽  
Holographic Dark Energy Model ◽  
Coincidence Problem ◽  
Accelerating Expansion ◽  
State 1

We investigate a kind of holographic dark energy model with a future event horizon being IR cutoff and the equation of state -1. In this model, the constraint on the equation of state automatically specifies an interaction between matter and dark energy. With this interaction included, an accelerating expansion is obtained as well as the transition from deceleration to acceleration. It is found that there exists a stable tracker solution for the numerical parameter d > 1, and d smaller than one will not lead to a physical solution. This model provides another possible phenomenological framework to alleviate the cosmological coincidence problem in the context of holographic dark energy. Some properties of the evolution which are relevant to cosmological parameters are also discussed.

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