Recovery of 21 cm BAO: a configuration-space correlation function analysis

TL;DR

This paper evaluates the effectiveness of different correlation function estimators in 21 cm intensity mapping for BAO detection, considering telescope beam and foreground effects, and forecasts constraints for upcoming experiments.

Contribution

It introduces a comprehensive pipeline for BAO measurement in IM using simulations, optimizing estimator choices, and providing forecasts for BINGO, MeerKAT, and SKA-mid.

Findings

Wedge correlation function provides the tightest BAO constraints for BINGO and MeerKAT.

Radial correlation function is most effective for SKA-mid's radial BAO.

The pipeline shows good agreement with mock catalogs and optimizes parameter choices for BAO detection.

Abstract

Intensity mapping (IM) represents an innovative and potent probe to cosmology. One of its prime applications is to measure the Baryonic Acoustic Oscillations (BAO) in the late universe. We study the BAO measurement by IM in configuration space using simulations, focusing on the impact of the telescope beam and foreground removal effects. Three types of correlation functions are applied to measure BAO, including the radial correlation function, multipole correlation function, and wedge correlation function. We check our pipeline against a set of IM mock catalogs, finding good agreement with the numerical results. We use the mock catalogs to look for the parameter choices that optimize the BAO constraint for the correlation function estimators. With the optimal settings, our pipeline is utilized to forecast the BAO constraint for the 21 cm IM experiments: BINGO, MeerKAT, and SKA-mid. We find that for the low redshift experiments BINGO and MeerKAT, the wedge correlation function achieves the tightest constraint for both the transverse and radial BAO. For SKA-mid, the radial correlation function and wedge correlation function deliver the tightest constraint for the radial and transverse BAO, respectively.