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

Anna Cabre; Enrique Gaztanaga

doi:10.1111/j.1365-2966.2009.14782.x

paper

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

arXiv:0807.2461 · doi:10.1111/j.1365-2966.2009.14782.x

Abstract

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 $Gp c^{3} / h^{3}$ 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 $r ≃ 10$ Mpc/h to $r ≃ 1$ 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.

13 pagfes, 24 figrues

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

Abstract

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