The real-space power spectrum of the PSCz survey from 0.01 to 300 h Mpc

We report a measurement of the real space (not redshift space) power spectrum of galaxies over four and a half decades of wavenumber, 0.01 to 300 hMpc, from the IRAS Point Source Catalog Redshift Survey (PSCz). Since estimates of power are highly correlated in the nonlinear regime, we also report results for the prewhitened power spectrum, which is less correlated. The inferred bias between optically-selected APM and IRAS-selected PSCz galaxies is about 1.15 at linear scales < ∼ 0.3 hMpc, increasing to about 1.4 at nonlinear scales > ∼ 1 hMpc. The nonlinear power spectrum of PSCz shows a near power-law behaviour to the smallest scales measured, with mild upward curvature in the broad vicinity of k ∼ 1.5 hMpc. Contrary to the prediction of unbiased Dark Matter models, there is no prominent inflection at the linearnonlinear transition scale, and no turnover at the transition to the stable clustering regime. The nonlinear power spectrum of PSCz requires scale-dependent bias: all Dark Matter models without scale-dependent bias are ruled out with high confidence.