Constraining β(z) and Ω⁰_m from redshift-space distortions in z~ 3 galaxy surveys

J. da Ângela, P. J. Outram, T. Shanks

Abstract
We use a sample of 813 Lyman-break galaxies (LBGs) with 2.6 < z < 3.4 to perform a detailed analysis of the redshift-space (z-space)distortions in their clustering pattern, and from that derive confidencelevels in the [Ω⁰_m, β(z= 3)] plane. We model the z-space distortions in the shape of the correlation function measured in orthogonal directions, ξ(σ, π). This modelling requires an accurate description of the real-space correlation function to be given as an input. From the projection of ξ(σ, π) in the angular direction, w_p (σ), we derive the best-fitting amplitude and slope for the LBG real-space correlation function: r₀= 4.48^+0.17_-0.18h^-1 Mpc and = 1.76^+0.08_-0.09[ξ(r) = (r/r₀)^-γ]. A comparison between the shape of ξ(s) and w_p (σ) suggests that ξ(r) deviates from a simple power-law model, with a break at ~9 h^-1 Mpc. This model is consistent with the observed projected correlation function. However, due to the limited size of the fields used, the w_p(σ) results are limited to σ<~ 10 h^-1 Mpc. Assuming this double-power-law model, and by analysing the shape distortions in ξ(σ, π), we find the following constraints: β(z= 3) = 0.15^+0.20_-0.15, Ω⁰_m= 0.35^+0.65_-0.22. Combining these results with orthogonal constraints from linear evolution of density perturbations, we find that β(z= 3) = 0.25^+0.05_-0.06, Ω⁰_m= 0.55^+0.45_-0.16.

Monthly Notices of the Royal Astronomical Society
Volume 361, Page 879
August 2005

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