Yungui Gong, Qing Gao, Zong-Hong Zhu
The constraints on $\Lambda$CDM model from type Ia supernova data alone and
BAO data alone are similar, so it is worthwhile to compare their constraints on
the property of dark energy. We use the SNLS3 compilation of 472 type Ia
supernova data, the Gamma Ray Bursts data, the baryon acoustic oscillation
measurement of distance, the cosmic microwave background radiation data from
the seven year Wilkinson Microwave Anisotropy Probe, and the Hubble parameter
data to study the effect of their different combinations on the fittings of
cosmological parameters. Neither BAO nor WMAP7 data alone gives good constraint
on the equation of state parameter of dark energy, but both WMAP7 data and BAO
data help type Ia supernova data break the degeneracies among the model
parameters, hence tighten the constraint on the variation of equation of state
parameter $w_a$, and WMAP7 data does the job a little better. Although BAO and
WMAP7 data provide reasonably good constraints on $\Omega_m$ and $\Omega_k$, it
is not able to constrain the dynamics of dark energy, we need SNe Ia data to
probe the property of dark energy, especially the variation of the equation of
state parameter of dark energy. The addition of $H(z)$ data helps better
constrain the geometry of the universe $\Omega_k$ and the property of dark
energy. For the SNLS SNe Ia data, the nuisance parameters $\alpha$ and $\beta$
are consistent for all different combinations of the above data. Their impacts
on the fittings of cosmological parameters are minimal. $\Lambda$CDM model is
consistent with all the observational data and it is favored against
Dvali-Gabadadze-Porrati model.
View original:
http://arxiv.org/abs/1110.6535
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