Hunting down systematics in baryon acoustic oscillations after cosmic high noon

TL;DR

This study uses high-precision N-body simulations to analyze systematic shifts and damping of BAO features caused by nonlinear growth, bias, and redshift-space distortions, providing detailed parametrizations for future dark energy research.

Contribution

It offers the first high-accuracy quantification of BAO shifts and damping across different biases, redshifts, and in redshift-space, with new parametrizations and insights into halo bias modulation.

Findings

BAO shifts are about 0.25% in real space, with no significant redshift evolution.

Damping of BAO features varies with halo bias and is less in halos than in dark matter.

Redshift-space distortions increase BAO shift and damping, explained by linear theory.

Abstract

Future dark energy experiments will require better and more accurate theoretical predictions for the baryonic acoustic oscillations (BAO) signature in the spectrum of cosmological perturbations. Here, we use large N-body simulations of the \LambdaCDM Planck cosmology to study any possible systematic shifts and damping in BAO due to the impact of nonlinear gravitational growth of structure, scale dependent and non-local bias, and redshift-space distortions. The effect of cosmic variance is largely reduced by dividing the tracer power spectrum by that from a BAO-free simulation starting with the same phases. This permits us to study with unprecedented accuracy (better than 0.02% for dark matter and 0.07% for low-bias halos) small shifts of the pristine BAO wavenumbers towards larger k, and non-linear damping of BAO wiggles in the power spectrum of dark matter and halo populations in the redshift range z=0-1. For dark matter, we provide an accurate parametrization of the evolution of \alpha as a function of the linear growth factor D(z). For halo samples, with bias ranging from 1.2 to 2.8, we measure a typical BAO shift of ~0.25%, observed in real-space, which does not show an appreciable evolution with redshift within the uncertainties. Moreover, we report a constant shift as a function of halo bias. We find a different evolution of the damping of the acoustic feature in all halo samples as compared to dark matter with haloes suffering less damping, and also find some weak dependence on bias. A larger BAO shift and damping is measured in redshift-space which can be well explained by linear theory due to redshift-space distortions. A clear modulation in phase with the acoustic scale is observed in the scale-dependent halo bias due to the presence of the baryonic acoustic oscillations.