Distribution function approach to redshift space distortions. Part V: perturbation theory applied to dark matter halos

TL;DR

This paper develops a perturbation theory-based model for redshift space distortions in dark matter halos, accurately capturing scale-dependent effects observed in simulations without free parameters, thus improving cosmological analysis.

Contribution

It introduces a halo biasing model combined with perturbation theory within the distribution function approach to accurately model RSD effects in halos.

Findings

Achieves percent-level accuracy up to k~0.15h/Mpc at z=0

Reproduces simulation results without free Fingers-of-God parameters

Models scale dependence of RSD in halos effectively

Abstract

Numerical simulations show that redshift space distortions (RSD) introduce strong scale dependence in the power spectra of halos, with ten percent deviations relative to linear theory predictions even on relatively large scales (k<0.1h/Mpc) and even in the absence of satellites (which induce Fingers-of-God, FoG, effects). If unmodeled these effects prevent one from extracting cosmological information from RSD surveys. In this paper we use perturbation theory (PT) and halo biasing model and apply it to the distribution function approach to RSD, in which RSD is decomposed into several correlators of density weighted velocity moments. We model each of these correlators using PT and compare the results to simulations over a wide range of halo masses and redshifts. We find that with an introduction of a physically motivated halo biasing, and using dark matter power spectra from simulations, we can reproduce the simulation results at a percent level on scales up to k~0.15h/Mpc at z=0, without the need to have free FoG parameters in the model.