Zhuo-Peng Huang, Yue-Liang Wu
We present a best-fit analysis on the holographic dark energy model
characterized by the conformal-age-like length. Based on the Union2 compilation
of 557 supernova Ia data, the baryon acoustic oscillation results from the
Sloan Digital Sky Survey data release 7, the cosmic microwave background
radiation data from the 7-yr Wilkinson Microwave Anisotropy Probe and the
Hubble constant measurement from the Wide Field Camera 3 on the Hubble Space
Telescope, we show that the model gives the minimal $\chi^2_{min}=549.428$,
which is comparable to $\chi^2_{\Lambda {\rm CDM}}=546.478$ for the
$\Lambda$CDM model. The single parameter $d$ concerned in the model is found to
be $d=0.235^{+0.005}_{-0.005} ^{+0.008}_{-0.009}$ at 1 $\sigma$ and 2 $\sigma$
confidence levels. The resulting constraints on the present fractional energy
density of matter and the equation of state are
$\Omega_{m}=0.278^{+0.017}_{-0.016} ^{+0.028}_{-0.026}$ and
$w_{de}=-1.252^{+0.025}_{-0.025} ^{+0.042}_{-0.041}$ respectively. The model
leads to a slightly larger fraction of matter comparing to the $\Lambda$CDM
model. 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 $w_{de}>-1$ to $w_{de}<-1$, 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 $\Lambda$CDM model.
View original:
http://arxiv.org/abs/1202.3517
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