A High Reliability Survey of Discrete Epoch of Reionization Foreground Sources in the MWA EoR0 Field

Abstract

Detection of the Epoch of Reionization HI signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182 MHz detected in the RA=0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sources have a median spectral index of -0.85. Spectral flattening is seen toward lower frequencies with a median of -0.71 predicted at 182 MHz. The astrometric error is 7 arcsec. compared to a 2.3 arcmin. beam FWHM. The resulting catalogue covers approximately 1400 sq. deg. and is complete to approximately 80 mJy within half beam power. This provides the most reliable discrete source sky model available to date in the MWA EoR0 field for precision foreground subtraction.

Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal on June 30, 2016

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• Spectral Index of the Diffuse Radio Background Between 50 and 100 MHz
• The impact of interference excision on 21-cm Epoch of Reionization power spectrum analyses
• PUMA: The Positional Update and Matching Algorithm
• Science with the Murchison Widefield Array: Phase I Results and Phase II Opportunities
• A Map of Diffuse Radio Emission at 182 MHz to Enhance Epoch of Reionization Observations in the Southern Hemisphere
• The Role of the Instrumental Response in 21 cm EoR Power Spectrum Gridding Analyses
• Building models for extended radio sources: implications for Epoch of Reionisation science
• Delay-Weighted Calibration: Precision Calibration for 21 cm Cosmology with Resilience to Sky Model Error
• Foreground and sensitivity analysis for broad band (2D) 21cm--Ly-alpha and 21cm--H-alpha correlation experiments probing the Epoch of Reionization