Redshift-space distortions in the PSCz galaxy catalogue

We apply a spherical harmonic analysis to the Point Source Redshift Survey (PSCz), to compute the real-space galaxy power spectrum and the degree of r edshift distortion caused by peculiar velocities. We employ new parameter e igenvector and hierarchical data compression techniques, allowing a much la rger number of harmonic modes to be included, and correspondingly smaller e rror bars. Using 4644 harmonic modes, compressed to 2278, we find that the IRAS redshift-space distortion parameter is beta = 0.39(-0.12)(+0.14) and t he amplitude of galaxy clustering on a scale of k = 0.1h Mpc(-1) is Delta ( g,0.1) = 0.42 +/- 0.02. Combining these we find the amplitude of mass pertu rbations is Delta (m,0.1) = (0.16 +/- 0.04)Omega (-0.6)(m). While this is c ompatible with results from the cosmic microwave background (CMB), with a s mall degree of tilt, it disagrees with the amplitude of matter perturbation s estimated from the abundance of clusters by a factor of 2, independent of cosmology. A preliminary model fitting analysis combining the CMB with eit her the PSCz or cluster abundances shows that the cosmological matter densi ty parameter Omega (m) = 0.29 +/- 0.09, and the IRAS bias parameter b = 1.2 2 +/- 0.28. However, the cluster abundances suggest that Delta (m,0.1) = 0. 60 +/- 0.09 and n(s) = 0.96 +/- 0.03, while the PSCz requires Delta (m,0.1) = 0.34 +/- 0.05 and n(s) = 0.81 +/- 0.05. Given the physics of galaxy form ation is poorly constrained, we conclude that IRAS galaxies and mass are on ly partially correlated.