Theoretical Systematics of Future Baryon Acoustic Oscillation Surveys

TL;DR

This paper assesses the systematic uncertainties in BAO scale measurements from future galaxy surveys, introducing new models and simulations to improve the robustness and accuracy of these cosmological probes.

Contribution

It develops a Galilean-invariant infrared resummed model for BAO analysis, evaluates reconstruction schemes, and quantifies systematic effects across various survey conditions.

Findings

Pre-reconstruction BAO scale dependence is 0.1-0.2% for matter.

Post-reconstruction BAO shifts are below 0.1% with reduced model dependence.

Reconstruction conventions can affect the line-of-sight BAO scale by up to 0.3%.

Abstract

Future Baryon Acoustic Oscillation surveys aim at observing galaxy clustering over a wide range of redshift and galaxy populations at great precision, reaching tenths of a percent, in order to detect any deviation of dark energy from the $\LCDM$ model. We utilize a set of paired quasi-\Nb\, FastPM simulations that were designed to mitigate the sample variance effect on the BAO feature and evaluated the BAO systematics as precisely as $\sim 0.01\%$. We report anisotropic BAO scale shifts before and after density field reconstruction in the presence of redshift-space distortions over a wide range of redshift, galaxy/halo biases, and shot noise levels. We test different reconstruction schemes and different smoothing filter scales, and introduce physically-motivated BAO fitting models. For the first time, we derive a Galilean-invariant infrared resummed model for halos in real and redshift space. We test these models from the perspective of robust BAO measurements and non-BAO information such as growth rate and nonlinear bias. We find that pre-reconstruction BAO scale has moderate fitting-model dependence at the level of $0.1\%-0.2\%$ for matter while the dependence is substantially reduced to less than $0.07\%$ for halos. We find that post-reconstruction BAO shifts are generally reduced to below $0.1\%$ in the presence of galaxy/halo bias and show much smaller fitting model dependence. Different reconstruction conventions can potentially make a much larger difference on the line-of-sight BAO scale, upto $0.3\%$. Meanwhile, the precision (error) of the BAO measurements is quite consistent regardless of the choice of the fitting model or reconstruction convention.