The XXL Survey

XLI. Radio AGN luminosity functions based on the GMRT 610 MHz continuum observations^⋆

¹ Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
e-mail: bslaus@phy.hr
² Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
³ Center for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
⁴ Department of Astronomy, University of Geneva, ch. d’Ecogia 16, 1290 Versoix, Switzerland
⁵ INAF – Osservatorio Astronomico di Bologna, P. Gobetti 93/3, 40129 Bologna, Italy
⁶ ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
⁷ Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands
⁸ H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
⁹ INAF, IASF Milano, Via Corti 12, 20133 Milano, Italy
¹⁰ Chalmers University of Technology, Dept. of Space, Earth and Environment, Onsala Space Observatory, 439 92 Onsala, Sweden
¹¹ CSIRO Astronomy and Space Science, PO Box 1130, Bentley, WA 6102, Australia
¹² International Centre for Radio Astronomy Research (ICRAR), M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
¹³ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
¹⁴ Centre for Space Research, North-West University, Potchefstroom 2520, South Africa
¹⁵ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité 91191, Gif-sur-Yvette, France
¹⁶ Inter-University Centre for Astronomy and Astrophysics Ganeshkhind, Post Bag 4, Puné 411 007, India

Received: 4 December 2019
Accepted: 29 January 2020

Abstract

We study the space density evolution of active galactic nuclei (AGN) using the 610 MHz radio survey of the XXL-North field, performed with the Giant Metrewave Radio Telescope. The survey covers an area of 30.4 deg², with a beamsize of 6.5 arcsec. The survey is divided into two parts, one covering an area of 11.9 deg² with 1σ rms noise of 200 μJy beam⁻¹ and the other spanning 18.5 deg² with rms noise of 45 μJy beam⁻¹. We extracted the catalog of radio components above 7σ. The catalog was cross-matched with a multi-wavelength catalog of the XXL-North field (covering about 80% of the radio XXL-North field) using a likelihood ratio method, which determines the counterparts based on their positions and their optical properties. The multi-component sources were matched visually with the aid of a computer code: Multi-Catalog Visual Cross-Matching. A flux density cut above 1 mJy selects AGN hosts with a high purity in terms of star formation contamination based on the available source counts. After cross-matching and elimination of observational biases arising from survey incompletenesses, the number of remaining sources was 1150. We constructed the rest-frame 1.4 GHz radio luminosity functions of these sources using the maximum volume method. This survey allows us to probe luminosities of 23 ≲ log(L_1.4 GHz[W Hz⁻¹]) ≲ 28 up to redshifts of z ≈ 2.1. Our results are consistent with the results from the literature in which AGN are comprised of two differently evolving populations, where the high luminosity end of the luminosity functions evolves more strongly than the low-luminosity end.