Verifying the Australian MWA EoR pipeline II: fundamental limits of the AusEoRPipe and the impact of instrumental effects

TL;DR

This paper assesses the fundamental limits of the AusEoRPipe pipeline in detecting the 21-cm cosmological signal using realistic simulations, highlighting the impact of instrumental effects and sky modeling inaccuracies.

Contribution

It introduces a comprehensive simulation and analysis framework to quantify how instrumental systematics affect 21-cm signal detection in the MWA EoR experiment.

Findings

Over 90% of unresolved point source flux must be subtracted for signal recovery.

Diffuse emission removal is necessary due to inaccessible k-modes.

Incomplete sky models are the main source of leakage.

Abstract

Detection of the weak cosmological signal from high-redshift hydrogen demands careful data analysis and an understanding of the full instrument signal chain. Here we use the WODEN simulation pipeline to produce realistic data from the Murchison Widefield Array Epoch of Reionisation experiment, and test the effects of different instrumental systematics through the AusEoRPipe analysis pipeline. The simulations include a realistic full sky model, direction-independent calibration, and both random and systematic instrumental effects. Results are compared to matched real observations. We find that, (i) with a sky-based calibration and power spectrum approach we have need to subtract more than 90% of all unresolved point source flux (10mJy apparent) to recover 21-cm signal in the absence of instrumental effects; (ii) when including diffuse emission in simulations, some k-modes cannot be accessed, leading to a need for some diffuse emission removal; (iii) the single greatest cause of leakage is an incomplete sky model; (iv) other sources of errors, such as cable reflections, flagged channels and gain errors, impart comparable systematic power to one another, and less power than the incomplete skymodel.