用SDSS和2dFGRS测量重子声学振荡标度
Measuring the Baryon Acoustic Oscillation scale using the SDSS and 2dFGRS
摘要：
本文介绍了一种利用覆盖不同红移范围的星系样本的重子声学振荡（BAO）距离测量来约束一般宇宙学模型的方法，并将这种方法应用于分析SDSS和2dFGRS的样本。在2dFGRS和SDSS组合的主星系样本的聚类中检测到BAO，并测量z=0.2处的距离-红移关系。SDSS亮红星系团中的BAO测量了z=0.35处的距离-红移关系。利用相关误差的估计，对从这些样本和从组合样本计算的BAO的观测尺度进行联合分析，以约束距离测度D_V（z）=[（1+z）^2D_A^2cz/H（z）]^（1/3）的形式。这里D_A是角直径距离，H（z）是哈勃参数。这给出了r_s/D_V（0.2）=0.1980+/-0.0058和r_s/D_V（0.35）=0.1094+/-0.0033（1 sigma误差），相关系数为0.39，其中r_s是复合时的共动声视界尺度。匹配BAO以在所有红移处具有相同的测量标度，然后给出D_V（0.35）/D_V（0.2）=1.812+/-0.060。恢复的比率大致与较高红移的SNLS超新星数据对λ宇宙学的预测一致，但在低红移时确实需要稍强的宇宙学加速度。如果我们强迫宇宙学模型是平坦的，并使w为常数，那么结合SNLS数据，并包括CMB中WMAP测量的表观声学视界角，我们得到Om_m=0.249+/-0.018和w=-1.004+/-0.089。
英文摘要：
We introduce a method to constrain general cosmological models using Baryon Acoustic Oscillation (BAO) distance measurements from galaxy samples covering different redshift ranges, and apply this method to analyse samples drawn from the SDSS and 2dFGRS. BAO are detected in the clustering of the combined 2dFGRS and SDSS main galaxy samples, and measure the distance--redshift relation at z=0.2. BAO in the clustering of the SDSS luminous red galaxies measure the distance--redshift relation at z=0.35. The observed scale of the BAO calculated from these samples and from the combined sample are jointly analysed using estimates of the correlated errors, to constrain the form of the distance measure D_V(z)=[(1+z)^2D_A^2cz/H(z)]^(1/3). Here D_A is the angular diameter distance, and H(z) is the Hubble parameter. This gives r_s/D_V(0.2)=0.1980+/-0.0058 and r_s/D_V(0.35)=0.1094+/-0.0033 (1sigma errors), with correlation coefficient of 0.39, where r_s is the comoving sound horizon scale at recombination. Matching the BAO to have the same measured scale at all redshifts then gives D_V(0.35)/D_V(0.2)=1.812+/-0.060. The recovered ratio is roughly consistent with that predicted by the higher redshift SNLS supernovae data for Lambda cosmologies, but does require slightly stronger cosmological acceleration at low redshift. If we force the cosmological model to be flat with constant w, then we find Om_m=0.249+/-0.018 and w=-1.004+/-0.089 after combining with the SNLS data, and including the WMAP measurement of the apparent acoustic horizon angle in the CMB.
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