Constraining β( z ) and Ω 0 m from redshift‐space distortions in z ∼ 3 galaxy surveys

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 confidence levels in the [Ω 0 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: r 0 = 4.48 +0.17 −0.18 h −1 Mpc and γ= 1.76 +0.08 −0.09 [ξ( r ) = ( r / r 0 ) −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 , Ω 0 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 , Ω 0 m = 0.55 +0.45 −0.16 .