Precision modeling of redshift-space distortions from multi-point propagator expansion

TL;DR

This paper develops advanced theoretical models for redshift-space distortions in matter clustering using multi-point propagator expansion, achieving high accuracy in power spectra predictions up to the quadrupole moment, with some discrepancies in the hexadecapole at low redshift.

Contribution

It introduces a systematic, two-loop order perturbation theory approach for RSD that improves predictions of matter clustering statistics in redshift space.

Findings

Good agreement with N-body simulations up to quadrupole

Significant deviations in hexadecapole at low redshift

Highlights importance of accurate RSD damping modeling

Abstract

Using a full implementation of resummed perturbation theory (PT) from a multi-point propagator expansion, we put forward new theoretical predictions for the two-point statistics of matter fluctuations in redshift space. The predictions consistently include PT corrections up to the two-loop order and are based on an improved prescription of the redshift-space distortions (RSD) that properly takes into account their non-Gaussian impact from a systematic low-k expansion. In contrast to the previous studies that partly used standard PT calculations, the present treatment is able to provide a consistent prediction for both power spectra and correlation functions. These results are compared with $N$-body simulations with which a very good agreement is found up to the quadrupole moment. The theoretical predictions for the hexadecapole moment of the power spectra are however found to significantly departs from the numerical results at low redshift. We examine this issue and found it to be likely related to an improper modeling of the RSD damping effects on which this moment shows large dependence.