Epoch of Reionization Power Spectrum Limits from Murchison Widefield Array Data Targeted at EoR1 Field

Abstract

Current attempts to measure the 21cm Power Spectrum of neutral hydrogen during the Epoch of Reionization are limited by systematics which produce measured upper limits above both the thermal noise and the expected cosmological signal. These systematics arise from a combination of observational, instrumental, and analysis effects. In order to further understand and mitigate these effects, it is instructive to explore different aspects of existing datasets. One such aspect is the choice of observing field. To date, MWA EoR observations have largely focused on the EoR0 field. In this work, we present a new detailed analysis of the EoR1 field. The EoR1 field is one of the coldest regions of the Southern radio sky, but contains the very bright radio galaxy Fornax-A. The presence of this bright extended source in the primary beam of the interferometer makes the calibration and analysis of EoR1 particularly challenging. We demonstrate the effectiveness of a recently developed shapelet model of Fornax-A in improving the results from this field. We also describe and apply a series of data quality metrics which identify and remove systematically contaminated data. With substantially improved source models, upgraded analysis algorithms and enhanced data quality metrics, we determine EoR power spectrum upper limits based on analysis of the best $\sim$14-hours data observed during 2015 and 2014 at redshifts 6.5, 6.8 and 7.1, with the lowest $2\sigma$ upper limit at z=6.5 of ${\Delta }^2\le (73.78\mathrm{mK}{)}^2$ at $k=0.13\mathrm{h}\mathrm{Mp}{\mathrm{c}}^{-1}$, improving on previous EoR1 measurement results.

arXiv comment18 pages, 17 figures, Accepted for publication in MNRAS

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• Impact of the Primordial Stellar Initial Mass Function on the 21-cm Signal
• The large-scale 21-cm power spectrum from reionization
• Detecting the non-Gaussianity of the 21-cm signal during reionisation with the Wavelet Scattering Transform
• Impact of instrument and data characteristics in the interferometric reconstruction of the 21 cm power spectrum
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• Measurements of one-point statistics in 21 cm intensity maps via foreground avoidance strategy
• Automated Detection of Antenna Malfunctions in Large-N Interferometers: A Case Study with the Hydrogen Epoch of Reionization Array
• Probing the Epoch of Reionization using synergies of line intensity mapping