The XXL Survey

XI. ATCA 2.1 GHz continuum observations^⋆

¹ University of Zagreb, Physics Department, Bijenička cesta 32, 10002 Zagreb, Croatia
e-mail: vs@phy.hr
² International Centre for Radio Astronomy Research (ICRAR), M468, University of Western Australia, 35 Stirling Hwy, WA 6009, Australia
³ Istituto di Radioastronomia di Bologna – INAF, via P. Gobetti, 101, 40129 Bologna, Italy
⁴ INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁵ H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
⁶ INAF, IASF Milano, via Bassini 15, 20133 Milano, Italy
⁷ Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Blvd de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
⁸ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, 1290 Versoix, Switzerland
⁹ Dept. of Earth & Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
¹⁰ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
¹¹ Argelander Institut für Astronomie, Universität Bonn, 53121 Bonn, Germany
¹² Service d’Astrophysique AIM, CEA/DSM/IRFU/SAp, CEA Saclay, 91191 Gif-sur-Yvette, France
¹³ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁴ Dipartimento di Fisica e Astronomia Universita degli Studi di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy

Received: 23 June 2015
Accepted: 13 October 2015

Abstract

We present 2.1 GHz imaging with the Australia Telescope Compact Array (ATCA) of a 6.5 deg² region within the XXM-Newton XXL South field using a band of 1.1−3.1 GHz. We achieve an angular resolution of 4.7′′ × 4.2′′ in the final radio continuum map with a median rms noise level of 50 μJy/beam. We identify 1389 radio sources in the field with peak S/N ≥ 5 and present the catalogue of observed parameters. We find that 305 sources are resolved, of which 77 consist of multiple radio components. These number counts are in agreement with those found for the COSMOS-VLA 1.4 GHz survey. We derive spectral indices by a comparison with the Sydney University Molongolo Sky Survey (SUMSS) 843 MHz data. We find an average spectral index of − 0.78 and a scatter of 0.28, in line with expectations. This pilot survey was conducted in preparation for a larger ATCA program to observe the full 25 deg² southern XXL field. When complete, the survey will provide a unique resource of sensitive, wide-field radio continuum imaging with complementary X-ray data in the field. This will facilitate studies of the physical mechanisms of radio-loud and radio-quiet AGNs and galaxy clusters, and the role they play in galaxy evolution. The source catalogue is publicly available online via the XXL Master Catalogue browser and the Centre de Données astronomiques de Strasbourg (CDS).