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具有Brans-Dicke引力II的宇宙微波背景：用WMAP和SDSS数据的约束

Cosmic microwave background with Brans-Dicke gravity II: constraints with the WMAP and SDSS data

Fengquan Wu, Xuelei Chen

备注：
9 double column pages, 10 figures, minor revision
发表信息：
Phys.Rev.D82:083003,2010
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摘要：

利用协变形式主义的同伴文件（文件I）中开发的，我们得到的观测约束的Brans-Dicke模型在一个平坦的FLRW宇宙的宇宙学常数和冷暗物质。我们使用的CMB观测数据包括WMAP五年数据、ACBAR 2007数据、CBI偏振数据和BOOMERanG 2003飞行数据。对于大尺度结构，我们使用SDSS DR 4的LRG测量的物质功率谱数据。我们用一个新的参数$ζ=\ln(1/ω+1)$来参数化Brans-Dicke参数$ω$，并使用马尔可夫链蒙特卡罗方法来探索参数空间。我们发现，单独使用CMB数据，人们可以放置一些约束正$ζ$或$ω$，但负$ζ$或$ω$不能有效地约束。然而，通过额外的大规模结构数据，可以打破$ζ<0$的简并性。与$ζ$结合的$2σ$（95.5%）为$-0.00837<ζ<0.01018$（对应于$ω< -120.0$或$ω> 97.8$）。我们还获得了对$\dot{G}/G$的约束，即$G$目前的变化率，作为$-1.75 \times 10^{-12} \yr^{-1}<\dot{G}/G < 1.05 \times 10^{-12}\yr^{-1}$，以及$δG/G$，即$G$自重组时期以来的总变化，作为在$2σ$置信水平下的$ -0.083 < δ{G}/G < 0.095$。

英文摘要：

Using the covariant formalism developed in a companion paper (paper I), we derive observational constraint on the Brans-Dicke model in a flat FLRW universe with cosmological constant and cold dark matter. The CMB observations we use include the WMAP five year data, the ACBAR 2007 data, the CBI polarization data, and the BOOMERanG 2003 flight data. For the large scale structure we use the matter power spectrum data measured with the LRG survey of the SDSS DR4. We parameterize the Brans-Dicke parameter $ω$ with a new parameter $ζ=\ln(1/ω+1)$, and use the Markov-Chain Monte Carlo method to explore the parameter space. We find that using CMB data alone, one could place some constraint on positive $ζ$ or $ω$, but negative $ζ$ or $ω$ could not be constrained effectively. However, with additional large scale structure data, one could break the degeneracy at $ζ<0$. The $2σ$ (95.5%) bound on $ζ$ is $-0.00837<ζ<0.01018$ (corresponding to $ω< -120.0$ or $ω> 97.8$). We also obtained constraint on $\dot{G}/G$, the rate of change of $G$ at present, as $-1.75 \times 10^{-12} \yr^{-1}<\dot{G}/G < 1.05 \times 10^{-12}\yr^{-1}$, and $δG/G$, the total variation of $G$ since the epoch of recombination, as $ -0.083 < δ{G}/G < 0.095$ at $2σ$ confidence level.

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