Verifying the Australian MWA EoR pipeline I: 21-cm sky model and correlated measurement density

TL;DR

This paper develops a detailed 21-cm sky model and investigates measurement correlations in Fourier-space to verify the Australian Epoch of Reionisation pipeline's ability to recover the 21-cm signal in simulations.

Contribution

It introduces an accurate sky model for the WODEN simulation, verifies the power spectrum estimator's effectiveness, and quantifies measurement correlation effects with a correction factor.

Findings

Power spectrum estimator CHIPS can recover the 21-cm signal without foregrounds.

A gridding density correction factor of 2.651 is appropriate for certain data integrations.

Measurement correlations in Fourier-space are characterized and corrected for accurate power spectrum estimation.

Abstract

We present the first of two papers dedicated to verifying the Australian Epoch of Reionisation pipeline (AusEoRPipe) through simulation. The AusEoRPipe aims to disentangle 21-cm radiation emitted by gas surrounding the very first stars from contaminating foreground astrophysical sources, and has been in development for close to a decade. In this paper, we build an accurate 21-cm sky model that can be used by the WODEN simulation software to create visibilities containing a predictable 21-cm signal. We verify that the power spectrum estimator CHIPS can recover this signal in the absence of foregrounds. We also investigate how measurements in Fourier-space are correlated, and how their gridded density affects the power spectrum. We measure and fit for this effect using Gaussian-noise simulations of the MWA phase I layout. We find a gridding density correction factor of 2.651 appropriate for integrations equal to or greater than 30 minutes of data, which contain observations with multiple primary beam pointings and LSTs. Paper II of this series will use the results of this paper to test the AusEoRPipe in the presence of foregrounds and instrumental effects.