Baryon Acoustic Oscillations in 2D II: Redshift-space halo clustering in N-body simulations

TL;DR

This paper analyzes halo clustering in redshift space using N-body simulations, revealing large-scale amplitude enhancements and validating a perturbation theory model that accurately describes anisotropic clustering and BAO features.

Contribution

It demonstrates that a physically-motivated perturbation theory model outperforms the streaming model in describing redshift-space halo clustering, especially for biased samples.

Findings

Redshift-space halo power spectrum shows large-scale amplitude enhancement.

The perturbation theory model accurately reproduces the measured clustering.

Proper modeling of non-linear density-velocity coupling is crucial for BAO analysis.

Abstract

We measure the halo power spectrum in redshift space from cosmological N-body simulations, and test the analytical models of redshift distortions particularly focusing on the scales of baryon acoustic oscillations (BAOs). Remarkably, the measured halo power spectrum in redshift space exhibits a large-scale enhancement in amplitude relative to the real-space clustering, and the effect becomes significant for the massive or highly biased halo samples. These findings cannot be simply explained by the so-called streaming model frequently used in the literature. By contrast, a physically-motivated perturbation theory model developed in the previous paper reproduces the halo power spectrum very well, and the model combining a simple linear scale-dependent bias can accurately characterize the clustering anisotropies of halos in two dimensions, i.e., line-of-sight and its perpendicular directions. The results highlight the significance of non-linear coupling between density and velocity fields associated with two competing effects of redshift distortions, i.e., Kaiser and Finger-of-God effects, and a proper account of this effect would be important in accurately characterizing the BAOs in two dimensions.