Deep ASKAP EMU Survey of the GAMA23 field: Properties of radio sources

TL;DR

This paper presents ASKAP radio observations of the GAMA23 field, cataloging nearly 40,000 sources, identifying host galaxies, and discovering 63 giant radio galaxies, demonstrating ASKAP's capabilities for large-scale, high-resolution sky surveys.

Contribution

First wide-area, high-resolution ASKAP survey of the GAMA23 field with detailed source cataloging and host galaxy identification, including discovery of giant radio galaxies.

Findings

Cataloged 39,812 radio sources above 5σ threshold.

Identified hosts with GAMA spectroscopic redshifts for 5,934 sources.

Discovered 63 giant radio galaxies.

Abstract

We present the Australian Square Kilometre Array Pathfinder (ASKAP) observations of the Galaxy and Mass Assembly (GAMA)-23h field. The survey was carried out at 887.5 MHz and covers a 83 square degree field. We imaged the calibrated visibility data, taken as part of the Evolutionary Mapping of Universe (EMU) Early Science Programme, using the latest version of the ASKAPSoft pipeline. The final mosaic has an angular resolution of 10 arcsec and a central rms noise of around 38 $\mu$Jy beam$^{-1}$. The derived radio source catalogue has 39812 entries above a peak flux density threshold of 5$\sigma$. We searched for the radio source host galaxy counterparts using the GAMA spectroscopic (with an i-band magnitude limit of 19.2 mag) and multi-wavelength catalogues that are available as part of the collaboration. We identified hosts with GAMA spectroscopic redshifts for 5934 radio sources. We describe the data reduction, imaging, and source identification process, and present the source counts. Thanks to the wide area covered by our survey, we obtain very robust counts down to 0.2 mJy. ASKAP's exceptional survey speed, providing efficient, sensitive and high resolution mapping of large regions of the sky in conjunction with the multi-wavelength data available for the GAMA23 field, allowed us to discover 63 giant radio galaxies. The data presented here demonstrate the excellent capabilities of ASKAP in the pre-SKA era.