The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1: IV. Photometric redshifts and stellar masses
Year: 2021
Type: article
Abstract: The Low Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) is a sensitive, high-resolution 120-168 MHz survey split across multiple tiers over the northern sky. The first LoTSS Deep Fields data release consists of deep radio continuum imaging at 150 MHz of the Boötes, European Large Area Infrared Space Observatory Survey-North 1, and Lockman Hole fields, down to rms sensitivities of ~32, 20, and 22 μJy beam−1, respectively. In this paper we present consistent photometric redshift (photo-z) estimates for the optical source catalogues in all three fields - totalling over 7 million sources (~5 million after limiting to regions with the best photometric coverage). Our photo-z estimation uses a hybrid methodology that combines template fitting and machine learning and is optimised to produce the best possible performance for the radio continuum selected sources and the wider optical source population. Comparing our results with spectroscopic redshift samples, we find a robust scatter ranging from 1.6 to 2% for galaxies and 6.4 to 7% for identified optical, infrared, or X-ray selected active galactic nuclei. Our estimated outlier fractions (|zphot−zspec|/(1+zspec)>0.15) for the corresponding subsets range from 1.5 to 1.8% and 18 to 22%, respectively. Replicating trends seen in analyses of previous wide-area radio surveys, we find no strong trend in photo-z quality as a function of radio luminosity for a fixed redshift. We exploit the broad wavelength coverage available within each field to produce galaxy stellar mass estimates for all optical sources at z < 1.5. Stellar mass functions derived for each field are used to validate our mass estimates, with the resulting estimates in good agreement between each field and with published results from the literature. The redshift catalogues are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/648/A4 and at https://lofar-surveys.org/releases.html, as part of this data release.
Authors: Duncan, K. J., Kondapally, R., Brown, M. J. I., Bonato, M., Best, P. N., Röttgering, H. J. A., Bondi, M., Bowler, R. A. A., Cochrane, R. K., Gürkan, G., Hardcastle, M. J., Jarvis, M. J., Kunert-Bajraszewska, M., Leslie, S. K., Małek, K., Morabito, L. K., O'Sullivan, S. P., Prandoni, I., Sabater, J., Shimwell, T. W., Smith, D. J. B., Wang, L., Wołowska, A., Tasse, C.
Institutions: Leiden University, Royal Observatory, Leiden Observatory, Monash University, Osservatorio Astronomico di Padova, National Institute for Astrophysics, Istituto di Radioastronomia di Bologna, University of Oxford, Harvard University, Center for Astrophysics Harvard & Smithsonian, Commonwealth Scientific and Industrial Research Organisation, University of Hertfordshire, University of the Western Cape, Nicolaus Copernicus University, Centre National de la Recherche Scientifique, Aix-Marseille Université, Durham University, Dublin City University, Netherlands Institute for Radio Astronomy, University of Groningen, Space Research Organisation Netherlands, Rhodes University, Observatoire de Paris, Galaxies, Etoiles, Physique et Instrumentation, Université Paris Diderot
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3097576955