arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1010.2299astro-ph.CO
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关于SDSS主星系样本的公平性

On the fairness of the main galaxy sample of SDSS

Kelai Meng, Bin Ma, Jun Pan, Longlong Feng

摘要:

通量有限和体积有限的星系样本是根据SDSS数据发布DR4,DR6和DR7构建的,用于统计分析。测量了两点关联函数$ξ(s)$、三点关联函数$ζ_0$、投影两点关联函数$w_p$和成对速度色散$σ_{12}$,以检验星系样本对这些统计量是否公平。我们发现,随着SDSS天空覆盖范围的增加,限流样本的$ξ(s)$具有很强的鲁棒性,并且在低红移时对局域结构不敏感。但对于在大尺度$s>\sim 10\hmpc$下比$L^*$更暗的体积受限样品,DR 7的$ξ(s)$和$ζ_0$相对于DR 4和DR 6的偏差随着绝对量级的增大而增大。在弱非线性区域,在所有光度箱中不同数据释放的$ζ_0$之间没有一致性。此外,在比$-M_{r,0.1}=[18.5,19.5]$更暗的光度箱中的DR 7的体积受限样本的$w_p$显著更大,并且DR 7的两个最暗的体积受限样本的$σ_{12}$显示出与DR 4和DR 6的结果非常不同的尺度依赖性。我们的研究结果要求在理解SDSS暗星系样本的聚类分析结果以及弱非线性区域中SDSS体积有限样本的高阶统计量时谨慎。本文还对有限体积样品的$ξ(s)$的第一个过零点进行了研究和讨论。

英文摘要:

Flux-limited and volume-limited galaxy samples are constructed from SDSS data releases DR4, DR6 and DR7 for statistical analysis. The two-point correlation functions $ξ(s)$, monopole of three-point correlation functions $ζ_0$, projected two-point correlation function $w_p$ and pairwise velocity dispersion $σ_{12}$ are measured to test if galaxy samples are fair for these statistics. We find that with increment of sky coverage of SDSS, $ξ(s)$ of flux-limited sample is extremely robust and insensitive to local structures at low redshift. But for volume-limited samples fainter than $L^*$ at large scales $s>\sim 10\hmpc$, deviation of $ξ(s)$ and $ζ_0$ of DR7 to those of DR4 and DR6 increases with larger absolute magnitude. In the weakly nonlinear regime, there is no agreement between $ζ_0$ of different data releases in all luminosity bins. Furthermore, $w_p$ of volume-limited samples of DR7 in luminosity bins fainter than $-M_{r,0.1}=[18.5,19.5]$ are significantly larger, and $σ_{12}$ of the two faintest volume-limited samples of DR7 display very different scale dependence than results of DR4 and DR6. Our findings call for cautions in understanding clustering analysis results of SDSS faint galaxy samples, and higher order statistics of SDSS volume-limited samples in the weakly nonlinear regime. The first zero-crossing points of $ξ(s)$ of volume-limited samples are also investigated and discussed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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