The 2dF QSO Redshift Survey - XIII. A measurement of Λ from the quasi-stellar object power spectrum, P s(k≺, k⊥)

Journal article

We report on measurements of the cosmological constant, Λ, and the redshift space distortion parameter β= Ω m0.6/b, based on an analysis of the quasi-stellar object (QSO) power spectrum parallel and perpendicular to the observer's line of sight, P s(k≺, k⊥), from the final catalogue of the Two-Degree Field (2dF) QSO Redshift Survey. We derive a joint Λ - β constraint from the geometric and redshift-space distortions in the power spectrum. By combining this result with a second constraint based on mass clustering evolution, we break this degeneracy and obtain strong constraints on both parameters. Assuming a flat (Ω m + Ω λ = 1) cosmology and a Λ cosmology r(z) function to convert from redshift into comoving distance, we find best-fitting values of Ω λ = 0.71 -0.17+0.09 and β q(z ∼ 1.4) = 0.45 -0.11+0.09 Assuming instead an Einstein-de Sitter cosmology r(z) we find that the best-fitting model obtained, with Ω λ = 0.64 +0.16+0.11 and β q(z ∼ 1.4) = 0-40 -0.09+0.09, is consistent with the Λ r(z) results, and inconsistent with a Ω λ = 0 flat cosmology at over 95 per cent confidence.

Authors: Outram, P; Shanks, T; Boyle, B; Croom, S; Hoyle, F

• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 348
• Issue: 3
• Pages: 745-752
• Publication date: 2004-03-01
• DOI: 10.1111/j.1365-2966.2004.07348.x
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: Cosmology: observations; Large-scale structure of Universe; Quasars: general; Surveys