Information content of the non-linear matter power spectrum

Abstract

We use an ensemble of N-body simulations of the currently favoured (concordance) cosmo-logical model to measure the amount of information contained in the non-linear matter power spectrum about the amplitude of the initial power spectrum. Two surprising results emerge from this study: (i) that there is very little independent information in the power spectrum in the translinear regime (k ≈ 0.2 -0.8 h Mpc-1 at the present day) over and above the information at linear scales; and (ii) that the cumulative information begins to rise sharply again with increasing wavenumber in the non-linear regime. In the fully non-linear regime, the simulations are consistent with no loss of information during translinear and non-linear evolution. If this is indeed the case then the results suggest a picture in which translinear collapse is very rapid, and is followed by a bounce prior to virialization, impelling a wholesale revision of the HKLM-Peacock & Dodds formalism. © 2005 RAS.