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arXiv 1302.6015astro-ph.CO
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光谱和光度样品互相关的重子声学振荡

Baryon acoustic oscillations with the cross-correlation of spectroscopic and photometric samples

Atsushi J. Nishizawa, Masamune Oguri, Masahiro Takada

备注：
10 pages, 7 figures, accepted to MNRAS
发表信息：
MNRAS 433, 730 (2013)
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摘要：

重子声学振荡（BAO）实验需要对具有光谱红移的大尺度结构示踪剂进行足够密集的采样，这在观测上是昂贵的，特别是在高红移$z\simgt 1$处。在这里，我们提出了一种替代路线的BAO分析，使用稀疏的光谱示踪剂与更密集的光度样本的互相关，其中光谱示踪剂可以是类星体或明亮的，罕见的星系，更容易访问光谱。我们表明，测量的互相关作为一个函数的横向共动分离，而不是角分离避免涂抹的BAO功能，而不混合不同的尺度在不同的红移的投影，即使是一个广泛的红移切片$Δz\simeq 1$。测光样本的偏差、散射和灾难性红移误差仅影响互相关的整体归一化，当约束角直径距离时，互相关可以被边缘化。作为一个具体的例子，我们通过SDSS和BOSS光谱类星体样本的互相关预测了BAO几何测试的预期准确性，其中密集的光度星系样本被假设为与SDSS/BOSS调查区域完全重叠。我们表明，如果星系的光度红移误差$σ_z/(1+z)$优于10-20%的水平，这种互相关BAO分析可以使我们在$1\simlt z\simlt 3$上的每个红移仓测量角直径距离的分数精度达到10%。

英文摘要：

The baryon acoustic oscillation (BAO) experiment requires a sufficiently dense sampling of large-scale structure tracers with spectroscopic redshift, which is observationally expensive especially at high redshifts $z\simgt 1$. Here we present an alternative route of the BAO analysis that uses the cross-correlation of sparse spectroscopic tracers with a much denser photometric sample, where the spectroscopic tracers can be quasars or bright, rare galaxies that are easier to access spectroscopically. We show that measurements of the cross-correlation as a function of the transverse comoving separation rather than the angular separation avoid a smearing of the BAO feature without mixing the different scales at different redshifts in the projection, even for a wide redshift slice $Δz\simeq 1$. The bias, scatter, and catastrophic redshift errors of the photometric sample affect only the overall normalization of the cross-correlation which can be marginalized over when constraining the angular diameter distance. As a specific example, we forecast an expected accuracy of the BAO geometrical test via the cross-correlation of the SDSS and BOSS spectroscopic quasar sample with a dense photometric galaxy sample that is assumed to have a full overlap with the SDSS/BOSS survey region. We show that this cross-correlation BAO analysis allows us to measure the angular diameter distances to a fractional accuracy of about 10% at each redshift bin over $1\simlt z\simlt 3$, if the photometric redshift errors of the galaxies, $σ_z/(1+z)$, are better than 10-20% level.

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