Clipping the Cosmos II: Cosmological information from non-linear scales

Understand

We present a method for suppressing contributions from higher-order terms in perturbation theory, greatly increasing the amount of information which may be extracted from the matter power spectrum.

• In an evolved cosmological density field the highest density regions are responsible for the bulk of the nonlinear power.
• By suitably down-weighting these problematic regions we find that the one- and two-loop terms are typically reduced in amplitude by ~70 per cent and ~95 per cent respectively, relative to the linear power spectrum.
• This greatly facilitates modelling the shape of the galaxy power spectrum, potentially increasing the number of useful Fourier modes by more than two orders of magnitude.