Clustering of luminous red galaxies - II. Small-scale redshift-space distortions
Abstract
This is the second paper of a series where we study the clustering of luminous red galaxies (LRG) in the recent spectroscopic Sloan Digital Sky Survey (SDSS) data release, DR6, which has 75000 LRG covering over 1Gpc3h-3 for 0.15 < z < 0.47. Here, we focus on modelling redshift-space distortions in ξ(σ, π), the two-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 two-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 on 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 σ12 with the distance. We show how both quantities can be inferred from the ξ(σ, π) data. From r ~= 10Mpch-1 to r ~= 1Mpch-1, both the bias and σ12 are shown to increase by a factor of 2: from b = 2 to 4 and from σ12 = 400 to 800kms-1. The latter is in good agreement, within a 5 per cent accuracy in the recovered velocities, with direct velocity measurements in dark matter simulations with Ωm = 0.25 and σ8 = 0.85.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2009
- DOI:
- 10.1111/j.1365-2966.2009.14782.x
- arXiv:
- arXiv:0807.2461
- Bibcode:
- 2009MNRAS.396.1119C
- Keywords:
-
- galaxies: distances and redshifts;
- galaxies: evolution;
- cosmology: observations;
- Astrophysics
- E-Print:
- 13 pagfes, 24 figrues