The XXL Survey

XXXIX. Polarised radio sources in the XXL-South field

¹ Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK
e-mail: raje1@leicester.ac.uk
² HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
³ Physics Department, University of Zagreb, Bijenička cesta 32, 10002 Zagreb, Croatia
⁴ Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
⁵ International Centre for Radio Astronomy Research (ICRAR), University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia
⁶ CSIRO Astronomy and Space Science, 26 Dick Perry Ave, Kensington, WA 6151, Australia
⁷ Department of Astronomy, University of Cape Town, Private Bag X3, 7701 Rondebosch, South Africa
⁸ Dipartimento di Fisica e Astronomia, Alma Mater Studiorum, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
⁹ INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
¹⁰ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France

Received: 7 June 2019
Accepted: 31 October 2019

Abstract

Aims. We investigate the properties of the polarised radio population in the central 6.5 deg² of the XXL-South field observed at 2.1 GHz using the Australia Telescope Compact Array (ATCA) in 81 pointings with a synthesised beam of FWHM 5.2″. We also investigate the ATCA’s susceptibility to polarisation leakage.

Methods. We performed a survey of a 5.6 deg² subregion and calculated the number density of polarised sources. We derived the total and polarised spectral indices, in addition to comparing our source positions with those of X-ray-detected clusters. We measured the polarisation of sources in multiple pointings to examine leakage in the ATCA.

Results. We find 39 polarised sources, involving 50 polarised source components, above a polarised flux density limit of 0.2 mJy at 1.332 GHz. The number density of polarised source components is comparable with recent surveys, although there is an indication of an excess at ∼1 mJy. We find that those sources coincident with X-ray clusters are consistent in their properties with regard to the general population. In terms of the ATCA leakage response, we find that ATCA mosaics with beam separation of ≲2/3 of the primary beam FWHM have off-axis linear polarisation leakage ≲1.4% at 1.332 GHz.