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arXiv 0807.2461astro-ph
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亮红色星系II的成团:小尺度红移空间畸变

Clustering of luminous red galaxies II: small scale redshift space distortions

Anna Cabre, Enrique Gaztanaga

摘要:

这是一个系列的第二篇论文,我们研究了在最新的光谱SDSS数据发布,DR 6,其中有75000 LRG星系覆盖超过1 $Gpc^3/h^3$为$0.15<z<0.47$的LRG星系的集群。在这里,我们专注于建模红移空间失真的$\xisp$,在单独的视线和垂直方向的2点相关,在小尺度和视线。我们表明,一个简单的Kaiser模型的各向异性的2点相关函数在红移空间,卷积与随机的特殊速度的分布与指数形式,可以很好地描述在所有尺度的相关LRG。我们表明,准确地描述了所谓的“上帝的手指”(FOG)在径向方向上的伸长,它是必要的模型的规模依赖的偏置$b$和成对的均方根特有的速度$σ_{12}$与距离。我们展示了如何从$\xisp$数据中推断出这两个量。从$r \simeq 10$ Mpc/h到$r \simeq 1$ Mpc/h,偏差和$σ_{12}$都显示出增加两倍:从$b=2$到$b=4$,从$σ_{12}=400$到800 Km/s。后者是在良好的协议,在5%的精度恢复速度,直接速度测量暗物质模拟与$Ω_m=0.25$和$σ_8$ =0.85。

英文摘要:

This is the second paper of a series where we study the clustering of LRG galaxies in the latest spectroscopic SDSS data release, DR6, which has 75000 LRG galaxies covering over 1 $Gpc^3/h^3$ for $0.15<z<0.47$. Here we focus on modeling redshift space distortions in $\xisp$, the 2-point correlation in separate line-of-sight and perpendicular directions, at small scales and in the line-of-sight. We show that a simple Kaiser model for the anisotropic 2-point correlation function in redshift space, convolved with a distribution of random peculiar velocities with an exponential form, can describe well the correlation of LRG at all scales. We show that to describe with accuracy the so called "fingers-of-God" (FOG) elongations in the radial direction, it is necessary to model the scale dependence of both bias $b$ and the pairwise rms peculiar velocity $σ_{12}$ with the distance. We show how both quantities can be inferred from the $\xisp$ data. From $r \simeq 10$ Mpc/h to $r \simeq 1$ Mpc/h, both the bias and $σ_{12}$ are shown to increase by a factor of two: from $b=2$ to $b=4$ and from $σ_{12}=400$ to 800 Km/s. The later is in good agreement, within a 5 percent accuracy in the recovered velocities, with direct velocity measurements in dark matter simulations with $Ω_m=0.25$ and $σ_8$=0.85.

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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