Inferring the Linear Power Spectrum from the Lyman-α Forest

We discuss the determination of the linear power spectrum of dark matter fluctuations from measurements of the transmitted flux Ly-α Forest power spectrum. We show that at most scales probed by current measurements, the flux power spectrum is significantly affected by non-linear corrections to the linear dark matter power spectrum due to gravitational clustering. Inferring the linear dark matter power spectrum shape is therefore difficult due to non-linear corrections driving the non-linear power spectrum to a k shape nearly independent of initial conditions. We argue that some methods used in previous estimates underestimate the uncertainties in the shape of the linear dark matter power spectrum. Subject headings: cosmology: theory – intergalactic medium – large scale structure of universe; quasars – absorption lines