Redshift Space Distortion Reconstruction

TL;DR

This paper develops and calibrates an accurate analytic reconstruction function for redshift space distortions in the matter power spectrum using simulations, improving modeling of nonlinear and velocity effects in cosmology.

Contribution

It advances the Kwan, Lewis, Linder (2012) reconstruction method by calibrating it with simulations and deriving a new analytic mapping for nonlinear real space power spectrum.

Findings

Achieves 2-5% accuracy in redshift space power spectrum modeling.

Derives RealEasy, an accurate nonlinear real space power spectrum mapping.

Demonstrates a complementary approach with 2-4% accuracy for higher wavenumbers.

Abstract

Redshift space distortions of the matter density power spectrum carry information on the growth rate of cosmic structure but require accurate modeling of nonlinear and velocity effects on the density field. We test and advance the reconstruction function of Kwan, Lewis, Linder (2012) in several ways. First, we compare to the distribution function perturbative approach of Seljak & McDonald (2012), deriving the mapping between them and showing how the KLL form can extend the validity of the latter. Second, using cosmological simulations rather than perturbation theory we calibrate the free functions within the KLL reconstruction form and fit their behavior in redshift and wavenumber. An efficient, new analysis pipeline rapidly calculates from simulation outputs the redshift space power spectrum. The end result is a robust analytic reconstruction function mapping the linear, real space matter power spectrum to the nonlinear, anisotropic redshift space power spectrum to an accuracy of ~2-5% in the range k=0.1-0.5 h/Mpc for z=0-2. As a by-product we derive RealEasy, an analytic mapping to the nonlinear, real space matter power spectrum (i.e. an analog to Halofit) to ~1% accuracy over the same range. We also investigate an approach converse to KLL and find it to be complementary and capable of achieving an accuracy of ~2-4% over the range k=0.3-1 h/Mpc for z=0-2.