Spherical harmonic analysis of redshift space distortions in the IRAS PSCz redshift survey

We apply the formalism of spherical harmonic decomposition to the galaxy density field of the IRAS PSCz redshift survey. Taking into account the first order distortion of the galaxy pattern due to redshift coordinates, we have measured the degree of distortion, parameterised by the distortion parameter beta = Omega(0.6)/b, Using maximum likelihood methods. We simultaneously measure either the undistorted amplitude of perturbations in the galaxy distribution when a parameterised power spectrum is assumed, or the shape and amplitude of the real-space power spectrum if the band-power in a set of passbands is measured in a step-wise fashion. We find that in the case of a parameterised power spectrum beta = 0.59 +/- 0.26 and the amplitude of the power at wavenumber k = 0.1hMpc(-1) is Delta(0.1) = 0.48 +/- 0.04 (marginal errors). Freeing the shape of the power spectrum we find that beta = 0.61 +/- 0.2, and Delta(0.1) = 0.48 +/- 0.04 (conditional errors).