The LOFAR Two-metre Sky Survey IV. First Data Release: Photometric redshifts and rest-frame magnitudes

K. Duncan, J. Sabater, H. Rottgering, M. Jarvis, D. Smith
2018 Astronomy and Astrophysics  
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 71μJy/beam and a resolution of 6". In this paper we present photometric redshifts (photo-z) for 94.4 this region that are detected in the Panoramic
more » ... ey 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 fraction ( | z_phot - z_spec | / (1+z_spec) > 0.15) of 7.9 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.
doi:10.1051/0004-6361/201833562 fatcat:eznbszfk2jallmgcuy3fms63am