Clipping the cosmos. II. Cosmological information from nonlinear scales

Fergus Simpson, Alan F. Heavens, Catherine Heymans

Research output: Contribution to journalArticlepeer-review


We present a method for suppressing contributions from higher-order terms in perturbation theory, greatly increasing the amount of information that 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 similar to 70% and similar to 95%, respectively, relative to the linear power spectrum. This greatly facilitates modeling the shape of the galaxy power spectrum, potentially increasing the number of useful Fourier modes by more than 2 orders of magnitude. We provide a demonstration of how this technique allows the galaxy bias and the amplitude of linear matter perturbations sigma(8) to be determined from the power spectrum on conventionally nonlinear scales, 0.1 <k <0.7 hMpc(-1).

Original languageEnglish
Article number083510
Number of pages12
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number8
Publication statusPublished - 10 Oct 2013



Cite this