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 redshift distortion caused by peculiar velocities. We employ new parameter eigenvector and hierarchical data compression techniques, allowing a much larger number of harmonic modes to be included, and correspondingly smaller error bars. Using 4644 harmonic modes, compressed to 2278, we find that the IRAS redshift-space distortion parameter is and the amplitude of galaxy clustering on a scale of is . Combining these we find the amplitude of mass perturbations is . While this is compatible with results from the cosmic microwave background (CMB), with a small degree of tilt, it disagrees with the amplitude of matter perturbations estimated from the abundance of clusters by a factor of 2, independent of cosmology. A preliminary model fitting analysis combining the CMB with either the PSCz or cluster abundances shows that the cosmological matter density parameter , and the IRAS bias parameter . However, the cluster abundances suggest that and , while the PSCz requires and . Given the physics of galaxy formation is poorly constrained, we conclude that IRAS galaxies and mass are only partially correlated.