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.

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

References in corpus (23)

• Scikit-learn: Machine Learning in Python
• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. II. The Source Catalogue
• The Murchison Widefield Array: Design Overview
• Science with the Murchison Widefield Array
• Post-correlation radio frequency interference classification methods
• GLEAM: The GaLactic and Extragalactic All-sky MWA survey
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr)
• Compact continuum source-finding for next generation radio surveys
• Calibration Requirements for Detecting the 21 cm Epoch of Reionization Power Spectrum and Implications for the SKA
• Correcting direction-dependent gains in the deconvolution of radio interferometric images
• Foregrounds in Wide-Field Redshifted 21 cm Power Spectra
• Probabilistic Cross-Identification of Astronomical Sources
• Fast Holographic Deconvolution: a new technique for precision radio interferometry
• The LOFAR Multifrequency Snapshot Sky Survey (MSSS) I. Survey description and first results
• Confirmation of Wide-Field Signatures in Redshifted 21 cm Power Spectra
• The Importance of Wide-field Foreground Removal for 21 cm Cosmology: A Demonstration With Early MWA Epoch of Reionization Observations
• A Fast Gridded Method for the Estimation of the Power Spectrum of the CMB from Interferometer Data with Application to the Cosmic Background Imager
• Parametrising Epoch of Reionization foregrounds: A deep survey of low-frequency point-source spectra with the MWA
• The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14,110 Compact Radio Sources over 6,100 Square Degrees
• The ASKAP/EMU Source Finding Data Challenge
• Software Holography: Interferometric Data Analysis for the Challenges of Next Generation Observatories
• Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array

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• Hydrogen Epoch of Reionization Array (HERA)
• Data Analysis for Precision 21 cm Cosmology
• Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
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• First Season MWA EoR Power Spectrum Results at Redshift 7
• Improving the Epoch of Reionization Power Spectrum Results from Murchison Widefield Array Season 1 Observations
• The Impact of Modeling Errors on Interferometer Calibration for 21 cm Power Spectra
• Fundamental Limitations on the Calibration of Redundant 21 cm Cosmology Instruments and Implications for HERA and the SKA
• Understanding the Diversity of 21 cm Cosmology Analyses
• 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
• Comparing Redundant and Sky Model Based Interferometric Calibration: A First Look with Phase II of the MWA
• DAYENU: A Simple Filter of Smooth Foregrounds for Intensity Mapping Power Spectra
• Source counts and confusion at 72-231 MHz in the MWA GLEAM survey
• 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
• Quantifying EoR delay spectrum contamination from diffuse radio emission
• 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