Radio AGN selection in LoTSS DR2
ABSTRACT The wide-area component of the LOFAR Two-Metre Sky Survey (LoTSS) is currently the largest radio survey ever carried out, and a large fraction of the 4.5 million radio sources it contains have been optically identified with galaxies or quasars with spectroscopic or photometric redshifts. Identification of radio-luminous active galactic nucleus (AGN) from this LoTSS source catalogue is not only important from the point of view of understanding the accretion history of the universe, but also enables a wide range of other science. However, at present the vast majority of the optical identifications lack spectroscopic information or well-sampled spectral energy distributions. We show that colour and absolute magnitude information from the Wide-Field Infrared Survey Explorer (WISE) allows for the robust and efficient selection of radio AGN candidates, generating a radio AGN candidate sample of around 600 000 objects with flux density $> 1.1$ mJy, spanning 144-MHz luminosities between $10^{21}$ and $10^{29}$ W Hz$^{-1}$. We use the catalogue to constrain the total sky density of radio-luminous AGN and the evolution of their luminosity function between $z=0$ and $z\approx 1$, and show that the typical mass of their host galaxies, around $10^{11} {\rm M}_\odot$, is essentially independent of radio luminosity above around $L_{144} \approx 10^{24}$ W Hz$^{-1}$. Combining with Very Large Array Sky Survey (VLASS) data, we show that the core prominences, radio spectral indices and variability of extended sources from the sample are qualitatively consistent with the expectations from unified models. A catalogue of the radio AGN candidates is released with this paper.
Authors
- B. Mingo (ORCID: https://orcid.org/0000-0001-5649-938X)
- H. J. A. Röttgering (ORCID: https://orcid.org/0000-0001-8887-2257)
- K. J. Duncan (ORCID: https://orcid.org/0000-0001-6889-8388)
- Yongwei Gong (ORCID: https://orcid.org/0000-0001-5439-6635)
- M. A. Horton (ORCID: https://orcid.org/0000-0003-4560-4150)
- J C S Pierce (ORCID: https://orcid.org/0000-0002-8250-9083)
- M. J. Hardcastle (ORCID: https://orcid.org/0000-0003-4223-1117)
- G. Gürkan (ORCID: https://orcid.org/0000-0002-9777-1762)
- D J B Smith
Institutions
- Leiden University (NL)
- Commonwealth Scientific and Industrial Research Organisation (AU)
- Australia Telescope National Facility (AU)
- University of Hertfordshire (GB)
- The Open University (GB)
- Bridge University (SS)
- Royal Observatory (GB)
- UK Astronomy Technology Centre (GB)
Publication Details
- Journal
- Monthly Notices of the Royal Astronomical Society
- Published
- 2025-04-12
- DOI
- https://doi.org/10.1093/mnras/staf622
- Citations
- 9
- Primary Topic
- Advanced Data Compression Techniques
- Type
- article
- Field-Weighted Citation Impact
- 11.48
Funders
- National Science Foundation
- U.S. Department of Energy
- University of Pennsylvania
- Ohio State University
- University of Chicago
- University of Portsmouth
- University College London
- University of Sussex
- University of Hertfordshire
- Science Foundation Ireland
- Deutsche Forschungsgemeinschaft
- Bundesministerium für Bildung und Forschung
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Max-Planck-Gesellschaft
- Centre National de la Recherche Scientifique
- Financiadora de Estudos e Projetos
- Istituto Nazionale di Astrofisica
- Université d'Orléans
- Ministerium für Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen
- Gauss Centre for Supercomputing
- University of Illinois at Urbana-Champaign
- Observatoire de Paris, Université de Recherche Paris Sciences et Lettres
- Science and Technology Facilities Council
- Integrated Electronics Engineering Center, Binghamton University
- DST-NRF Centre Of Excellence In Tree Health Biotechnology
- Argonne National Laboratory
- Fermilab
- Lawrence Berkeley National Laboratory
- SLAC National Accelerator Laboratory