Recovery of the shape of the mass power spectrum from the Lyα forest

We propose a method for recovering the shape of the mass power spectrum on large scales from the transmission fluctuations of the Ly alpha forest that directly takes into account redshift-space distortions. The procedure, in discretized form, involves the inversion of a triangular matrix that projects the mass power spectrum in three-dimensional real space to the transmission power spectrum in one-dimensional redshift space. We illustrate the method by performing a linear calculation relating the two. A method that does not take into account redshift-space anisotropy tends to underestimate the steepness of the mass power spectrum in the case of linear distortions. The issue of the effective bias factor for the linear distortion kernel is discussed.