The XXL Survey : XXVI. Optical and near-infrared identifications of the ATCA 2.1 GHz radio sources in the XXL-S Field

Abstract

In this paper we present the optical, near-infrared (NIR) and X-ray identifications of the 6287 radio sources detected in the 2.1 GHz deep radio survey down to a median rms of ~ 41microJy/beam obtained with the Australia Telescope Compact Array (ATCA) in the XXL-S field. The goal of this paper is to provide a multi wavelength catalogue of the counterparts of the radio sources to be used in further studies. For the optical and NIR identification of the radio sources, we used the likelihood ratio (LR) technique, slightly modified in order to take into account the presence of a large number of relatively bright counterparts close to the radio sources. This procedure led to the identification of optical/NIR counterparts for 4770 different radio sources (~77% of the whole radio sample), 414 of which also have an X-ray counterpart. This fraction of identification is in agreement with previous radio-optical association studies at a similar optical magnitude depth, but is relatively low in comparison to recent work conducted in other radio fields using deeper optical and NIR data. The analysis of optical and NIR properties of radio sources shows that, regardless of the radio flux limit of a radio survey, the nature of the identified sources is strongly dependent on the depth of the optical/NIR used in the identification process. Only with deep enough optical/NIR data will we be able to identify a significant fraction of radio sources with red (z_{DEC}-K) counterparts whose radio emission is dominated by nuclear activity rather than starburst activity.

arXiv comment11 pages, 11 figures, Accepted for publication in A&A

References in corpus (36)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Cosmic Evolution Survey (COSMOS) -- Overview
• The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release
• The VLA-COSMOS Survey: II. Source Catalog of the Large Project
• The Nature of Radio Emission from Distant Galaxies: The 1.4 GHz Observations
• The XXL Survey: I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme
• The Blanco Cosmology Survey: Data Acquisition, Processing, Calibration, Quality Diagnostics and Data Release
• The VLA-COSMOS Survey. IV. Deep Data and Joint Catalog
• VLA-COSMOS 3GHz Large Project: The infrared-radio correlation of star-forming galaxies and AGN to $z\lesssim 6$
• The VLA-COSMOS 3 GHz Large Project: Multiwavelength counterparts and the composition of the faint radio population
• The VLA-COSMOS 3~GHz Large Project: AGN and host-galaxy properties out to z$\lesssim$6
• The XMM-Newton wide-field survey in the COSMOS field: III. optical identification and multiwavelength properties of a large sample of X-ray selected sources
• The VLA-COSMOS 3 GHz Large Project: The cosmic star formation history since z~5
• Radio emission from Supernova Remnants
• Cosmic evolution of radio selected active galactic nuclei in the COSMOS field
• A new method to separate star forming from AGN galaxies at intermediate redshift: The submillijansky radio population in the VLA-COSMOS survey
• The VLA-VIRMOS Deep Field I. Radio observations probing the microJy source population
• A deep VLA survey at 6 cm in the Lockman Hole
• The VLA-COSMOS Survey: III. Further Catalog Analysis and the Radio Source Counts
• Radio Observations of the Hubble Deep Field South Region II: The 1.4 GHz Catalogue and Source Counts
• The VLA Survey of the Chandra Deep Field South. IV. Source Population
• PRIMUS: Infrared and X-ray AGN Selection Techniques at 0.2<z<1.2
• The dust un-biased cosmic star formation history from the 20 cm VLA-COSMOS survey
• The Radio/Optical Catalog of the SSA13 Field
• Optical identifications and spectroscopy of a faint radio source sample: the nature of the sub-mJy population
• The Phoenix Deep Survey: spectroscopic catalog
• The Canada-France Redshift Survey VII: Optical counterparts of microJansky radiosources
• The XXL Survey: VI. The 1000 brightest X-ray point sources
• The XXL Survey: XXVII. The 3XLSS point source catalogue
• The ATESP Radio Survey IV. Optical Identifications and Spectroscopy in the EIS-A Region
• The VVDS-VLA Deep Field II. Optical and near infrared identifications of VLA S(1.4GHz)>80 microJy sources in the VIMOS VLT Deep Survey VVDS-02h field
• Properties and environment of Radio Emitting Galaxies in the VLA-zCOSMOS survey
• The XXL Survey XVIII. ATCA 2.1 GHz radio source catalogue and source counts for the XXL-South field
• The XXL Survey: XXXI. Classification and host galaxy properties of 2.1 GHz ATCA XXL-S radio sources
• Radio and millimeter properties of $z\sim 5.7$ Ly$\alpha$ emitters in the COSMOS field: limits on radio AGN, submm galaxies, and dust obscuration
• The XXL Survey XI: ATCA 2.1 GHz continuum observations

Cited by in corpus (7)

• The LOFAR Two Metre Sky Survey: Deep Fields Data Release 1 -- III. Host-galaxy identifications and value added catalogues
• A new estimate of the cosmic star formation density from a radio-selected sample, and the contribution of $H$-dark galaxies at $z\ge 3$
• The XXL Survey: XXVII. The 3XLSS point source catalogue
• The XXL Survey: XXXVI. Evolution and black hole feedback of high-excitation and low-excitation radio galaxies in XXL-S
• The XXL Survey: XXXI. Classification and host galaxy properties of 2.1 GHz ATCA XXL-S radio sources
• The XXL Survey: XLIII. The quasar radio loudness dichotomy exposed via radio luminosity functions obtained by combining results from COSMOS and XXL-S X-ray selected quasars
• The XXL Survey. XLI. Radio AGN luminosity functions based on the GMRT $610\mathrm{MHz}$ continuum observations