Baryon Acoustic Oscillations in 2D: Modeling Redshift-space Power Spectrum from Perturbation Theory

TL;DR

This paper introduces an improved model for the redshift-space matter power spectrum that accurately accounts for non-linear gravitational clustering and redshift distortions, enhancing the precision of baryon acoustic oscillation measurements.

Contribution

The paper presents a novel perturbation theory-based model for redshift-space power spectra that includes non-linear coupling effects, outperforming previous phenomenological models.

Findings

Excellent agreement with N-body simulations over BAO scales

Systematic errors in previous models are reduced to below 2% for distance measurements

The new model improves constraints on dark energy and gravity from galaxy surveys

Abstract

We present an improved prescription for matter power spectrum in redshift space taking a proper account of both the non-linear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the non-linear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1~2%, and the growth rate parameter by ~5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription of redshift-space power spectrum including the non-linear corrections can be used as an accurate theoretical template for anisotropic BAOs.