The 2dF QSO redshift survey - XV. Correlation analysis of redshift-space distortions

We analyse the redshift-space (z-space) distortions of quasi-stellar object (QSO) clustering in the 2-degree field instrument (2dF) QSO Redshift Survey (2QZ). To interpret the z-space correlation function, xi(sigma, pi), we require an accurate model for the QSO real-space correlation function, xi(r). Although a single power-law xi( r) proportional to r(-gamma) model fits the projected correlation function [w(p)(sigma)] at small scales, it implies somewhat too shallow a slope for both w(p)(sigma) and the z-space correlation function, xi(s), at larger scales (greater than or similar to 20 h(-1) Mpc). Motivated by the form for. ( r) seen in the 2dF Galaxy Redshift Survey (2dFGRS) and in standard Lambda cold dark matter (CDM) predictions, we use a double power-law model for. ( r), which gives a good fit to. ( s) and wp( s). The model is parametrized by a slope of gamma = 1.45 for 1 < r < 10 h(-1) Mpc and gamma = 2.30 for 10 < r < 40 h(-1) Mpc. As found for the 2dFGRS, the value of beta determined from the ratio of xi(s)/xi( r) depends sensitively on the form of xi(r) assumed. With our double power-law form for xi(r), we measure beta(z = 1.4) = 0.32(-0.11)(+0.09) Assuming the same model for xi(r), we then analyse the z-space distortions in the 2QZ. ( s, p) and put constraints on the values of Omega(m)(0) and beta(z = 1.4), using an improved version of the method of Hoyle et al. The constraints we derive are Omega(m)(0) = 0.35(-0.13)(+0.19), beta(z = 1.4) = 0.50(-0.15)(+0.13) , in agreement with our xi(s)/xi(r) results at the similar to 1 sigma level.