The XXL Survey

XVIII. ATCA 2.1 GHz radio source catalogue and source counts for the XXL-South field^★

¹ International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, 35 Stirling Hwy, Crawley WA 6009, Australia
e-mail: andrew.butler@icrar.org
² CSIRO Astronomy and Space Science, 26 Dick Perry Ave, Kensington WA 6151, Australia
³ Physics Department, University of Zagreb, Bijenička cesta 32, 10002 Zagreb, Croatia
⁴ Western Sydney University, Locked Bag 1797, Penrith NSW 2751, Australia
⁵ INAF, IASF Milano, via Bassini 15, 20133 Milano, Italy
⁶ Department of Physics, IIT Hyderabad, Kandi, 502285 Telangana, India
⁷ Department of Astronomy, University of Geneva, Ch. d'Écogia 16, 1290 Versoix, Switzerland
⁸ Onsala Space Observatory, Department of Earth and Space Sciences, Chalmers University of Technology, 439 92 Onsala, Sweden
⁹ Australian Astronomical Observatory, 105 Delhi Rd, North Ryde NSW 2113, Australia
¹⁰ Service d'Astrophysique AIM, CEA/DRF/IRFU/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France

Received: 25 November 2016
Accepted: 12 March 2017

Abstract

The 2.1 GHz radio source catalogue of the 25 deg² ultimate XMM extragalactic survey south (XXL-S) field, observed with the Australia Telescope Compact Array (ATCA), is presented. The final radio mosaic achieved a resolution of ~ 4.8″ and a median rms noise of σ ≈ 41 μJy/beam. To date, this is the largest area radio survey to reach this flux density level. A total of 6350 radio components above 5σ are included in the component catalogue, 26.4% of which are resolved. Of these components, 111 were merged together to create 48 multiple-component radio sources, resulting in a total of 6287 radio sources in the source catalogue, 25.9% of which were resolved. A survival analysis revealed that the median spectral index of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz sources in the field is α = −0.75, consistent with the values of − 0.7 to − 0.8 commonly used to characterise radio spectral energy distributions of active galactic nuclei. The 2.1 GHz and 1.4 GHz differential radio source counts are presented and compared to other 1.4 GHz radio surveys. The XXL-S source counts show good agreement with the other surveys.