Journal Article

Clustering of luminous red galaxies – II. Small-scale redshift-space distortions

Anna Cabré and Enrique Gaztañaga

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 396, issue 2, pages 1119-1131
Published in print June 2009 | ISSN: 0035-8711
Published online June 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14782.x
Clustering of luminous red galaxies – II. Small-scale redshift-space distortions

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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 75 000 LRG covering over 1 Gpc3 h−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≃ 10 Mpc h−1 to r≃ 1 Mpc h−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 800 km s−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.

Keywords: galaxies: distances and redshifts; galaxies: evolution; cosmology: observations

Journal Article.  9026 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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