The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1
Astronomy and Astrophysics, vol. 648, pp. A4
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.
Authors 24
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Leiden University · Royal Observatory · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Affiliation as printed
School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia
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Istituto di Radioastronomia di Bologna · Osservatorio Astronomico di Padova · National Institute for Astrophysics
Affiliation as printed
INAF–Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
Italian ALMA Regional Centre, Via Gobetti 101, 40129 Bologna, Italy
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Istituto di Radioastronomia di Bologna
Affiliation as printed
INAF–Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
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Affiliation as printed
Astrophysics, Department of Physics, Keble Road, Oxford, OX1 3RH, UK
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Center for Astrophysics Harvard & Smithsonian
Affiliation as printed
Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USA
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Commonwealth Scientific and Industrial Research Organisation
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CSIRO Astronomy and Space Science, PO Box 1130, Bentley WA 6102, Australia
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Affiliation as printed
Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
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University of Oxford · University of the Western Cape
Affiliation as printed
Astrophysics, Department of Physics, Keble Road, Oxford, OX1 3RH, UK
Department of Physics & Astronomy, University of the Western Cape, Private Bag X17, Bellville, Cape Town 7535, South Africa
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Nicolaus Copernicus University
Affiliation as printed
Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, NCU, Grudziadzka 5, 87-100 Toruń, Poland
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Centre National de la Recherche Scientifique · Aix-Marseille Université · National Centre for Nuclear Research
Affiliation as printed
Aix-Marseille Univ. CNRS, CNES, LAM, Marseille, France
National Centre for Nuclear Research, ul. Pasteura 7, 02-093 Warszawa, Poland
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Affiliation as printed
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham, DH1 3LE, UK
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Affiliation as printed
School of Physical Sciences and Centre for Astrophysics & Relativity, Dublin City University, Glasnevin, D09 W6Y4, Ireland
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Osservatorio Astronomico di Padova · National Institute for Astrophysics
Affiliation as printed
INAF–Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
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Affiliation as printed
SUPA, Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
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Leiden University · Leiden Observatory · Netherlands Institute for Radio Astronomy
Affiliation as printed
ASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, 7991 PD, Dwingeloo, The Netherlands
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
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Affiliation as printed
Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
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University of Groningen · Space Research Organisation Netherlands
Affiliation as printed
Kapteyn Astronomical Institute, University of Groningen, Postbus 800, 9700 AV Groningen, The Netherlands
SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD, Groningen, The Netherlands
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Nicolaus Copernicus University
Affiliation as printed
Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, NCU, Grudziadzka 5, 87-100 Toruń, Poland
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Centre National de la Recherche Scientifique · Rhodes University · Observatoire de Paris · Galaxies, Etoiles, Physique et Instrumentation · Université Paris Diderot
Affiliation as printed
Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
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