The LOFAR Two-metre Sky Survey. IV. First Data Release: Photometric redshifts and rest-frame magnitudes
Journal
Date Issued
2019
Author(s)
Duncan, K. J.
•
Sabater, J.
•
Röttgering, H. J. A.
•
Jarvis, M. J.
•
Smith, D. J. B.
•
Best, P. N.
•
Callingham, J. R.
•
Cochrane, R.
•
Croston, J. H.
•
Hardcastle, M. J.
•
Mingo, B.
•
Morabito, L.
•
Nisbet, D.
•
•
Shimwell, T. W.
•
Tasse, C.
•
White, G. J.
•
Williams, W. L.
•
Alegre, L.
•
Chyży, K. T.
•
Gürkan, G.
•
Hoeft, M.
•
Kondapally, R.
•
Mechev, A. P.
•
Miley, G. K.
•
Schwarz, D. J.
•
van Weeren, R. J.
Abstract
The LOFAR Two-metre Sky Survey (LoTSS) is a sensitive, high-resolution 120-168 MHz survey of the Northern sky. The LoTSS First Data Release (DR1) presents 424 square degrees of radio continuum observations over the HETDEX Spring Field (10h45m00s < right ascension < 15h30m00s and 45°00'00″ < declination < 57°00'00″) with a median sensitivity of 71 μJy beam-1 and a resolution of 6″. In this paper we present photometric redshifts (photo-z) for 94.4% of optical sources over this region that are detected in the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) 3π steradian survey. Combining the Pan-STARRS optical data with mid-infrared photometry from the Wide-field Infrared Survey Explorer, we estimate photo-zs using a novel hybrid photometric redshift methodology optimised to produce the best possible performance for the diverse sample of radio continuum selected sources. For the radio-continuum detected population, we find an overall scatter in the photo-z of 3.9% and an outlier fraction (|zphot-zspec|/(1 + zspec) > 0.15) of 7.9%. We also find that, at a given redshift, there is no strong trend in photo-z quality as a function of radio luminosity. However there are strong trends as a function of redshift for a given radio luminosity, a result of selection effects in the spectroscopic sample and/or intrinsic evolution within the radio source population. Additionally, for the sample of sources in the LoTSS First Data Release with optical counterparts, we present rest-frame optical and mid-infrared magnitudes based on template fits to the consensus photometric (or spectroscopic when available) redshift.
LoTSS.The catalogue is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A1
Volume
622
Start page
A3
Issn Identifier
0004-6361
Ads BibCode
2019A&A...622A...3D
Rights
open.access
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