Wednesday, January 4, 2012

1110.6535 (Yungui Gong et al.)

The effect of different observational data on the constraints of cosmological parameters    [PDF]

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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