First Season MWA EoR Power Spectrum Results at Redshift 7

TL;DR

This paper presents new analysis techniques applied to MWA data to improve the upper limits on the EoR power spectrum at redshift 7, achieving a modest enhancement over previous results.

Contribution

Introduction of novel calibration and data analysis methods that enhance the sensitivity of EoR power spectrum measurements with the MWA.

Findings

Placed a systematic-limited upper limit of Δ² ≤ 2.7×10⁴ mK² at k=0.27 h Mpc⁻¹, z=7.1

Achieved a 1.4 times improvement over previous MWA results

Identified key analysis improvements for future EoR data processing

Abstract

The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch of Reionization (EoR) data and now faces the challenge of overcoming foreground and systematic contamination to reduce the data to a cosmological measurement. We introduce several novel analysis techniques such as cable reflection calibration, hyper-resolution gridding kernels, diffuse foreground model subtraction, and quality control methods. Each change to the analysis pipeline is tested against a two dimensional power spectrum figure of merit to demonstrate improvement. We incorporate the new techniques into a deep integration of 32 hours of MWA data. This data set is used to place a systematic-limited upper limit on the cosmological power spectrum of $\Delta^2 \leq 2.7 \times 10^4$ mK$^2$ at $k=0.27$ h~Mpc$^{-1}$ and $z=7.1$, consistent with other published limits, and a modest improvement (factor of 1.4) over previous MWA results. From this deep analysis we have identified a list of improvements to be made to our EoR data analysis strategies. These improvements will be implemented in the future and detailed in upcoming publications.