Application of Data Compression Methods to the Redshift-space distortions of 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 β = 0.39±0.12 and the amplitude of galaxy clustering on a scale of k = 0.1 hMpc is ∆gal(0.1) = 0.42±0.02. Combining these we find the amplitude of mass perturbations is ∆m(0.1) = (0.16± 0.04)Ω −0.6 m . A preliminary model fitting analysis combining the PSCz amplitudes with the CMB and abundance of clusters yields the cosmological matter density parameter Ωm = 0.16±0.03, the amplitude of primordial perturbations Q = (8.4± 3.8)× 10, and the IRAS bias parameter b = 0.84± 0.28.