Fermi Unassociated Sources in the MeerKAT Absorption Line Survey
Abstract Over 2000 γ -ray sources identified by the Large Area Telescope on NASA's Fermi Gamma-ray Space Telescope are considered unassociated, meaning that they have no known counterparts in any other frequency regime. We have carried out an image-based search for steep spectrum radio sources, with in-band spectral index < −1.4, within the error regions of Fermi unassociated sources using 1–1.4 GHz radio data from the MeerKAT Absorption Line Survey (MALS) data release. The first MALS data release with a median rms noise of 22–25 μ Jy and 735,649 sources is a significant advance over past image-based searches with improvements in sensitivity, resolution, and bandwidth. Steep spectrum candidates were identified using a combination of in-band spectral indices from MALS and existing radio surveys. We developed an optical and infrared source classification scheme in order to distinguish between Galactic pulsars and radio galaxies. In total, we identify nine pulsar candidates toward six Fermi sources that are worthy of follow-up for pulsation searches. We also report 41 steep spectrum radio galaxy candidates that may be of interest in searches for high-redshift radio galaxies. We show that MALS, due to its excellent continuum sensitivity, can detect 80% of the known pulsar population. This exhibits the promise of identifying exotic pulsar candidates with future image-based surveys with the Square Kilometre Array and its precursors.
Authors
- D. A. Frail (ORCID: https://orcid.org/0009-0008-7604-003X)
- P. P. Deka
- H.-R. Klöckner (ORCID: https://orcid.org/0000-0002-0648-2704)
- Morgan Himes (ORCID: https://orcid.org/0009-0004-1469-9550)
- N. Gupta (ORCID: https://orcid.org/0000-0001-7547-4241)
- F. K. Schinzel (ORCID: https://orcid.org/0000-0001-6672-128X)
- Françoise Combes (ORCID: https://orcid.org/0000-0003-2658-7893)
- P. Jagannathan (ORCID: https://orcid.org/0000-0002-5825-9635)
- J. D. Wagenveld (ORCID: https://orcid.org/0000-0003-1321-0886)
- S. A. Balashev (ORCID: https://orcid.org/0000-0002-3814-9666)
- Emmanuel Momjian (ORCID: https://orcid.org/0000-0003-3168-5922)
Institutions
- Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (FR)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-02-05
- DOI
- https://doi.org/10.3847/1538-4357/ada1cf
- Citations
- 1
- Primary Topic
- Astrophysics and Cosmic Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 1.87
Funders
- National Science Foundation
- Smithsonian Institution
- U.S. Department of Energy
- National Aeronautics and Space Administration
- Gordon and Betty Moore Foundation
- University of Pennsylvania
- Ohio State University
- California Institute of Technology
- University of Chicago
- Johns Hopkins University
- Science and Industry Endowment Fund
- University of Portsmouth
- Space Telescope Science Institute
- National Radio Astronomy Observatory
- Australian Government
- University of Sussex
- Queen's University Belfast
- Commonwealth Scientific and Industrial Research Organisation
- Durham University
- National Research Foundation
- Deutsche Forschungsgemeinschaft
- Chinese Academy of Sciences
- Queen's University
- Financiadora de Estudos e Projetos
- National Central University
- Eötvös Loránd Tudományegyetem
- Government of Western Australia
- Max-Planck-Institut für Astronomie
- University of Illinois at Urbana-Champaign
- Office of Science
- Jet Propulsion Laboratory
- University of California, Los Angeles
- Smithsonian Astrophysical Observatory
- Science Mission Directorate
- Science and Technology Facilities Council
- Division of Astronomical Sciences
- High Energy Physics
- Planetary Science Division
- Argonne National Laboratory
- Lawrence Berkeley National Laboratory
- Los Alamos National Laboratory
- SLAC National Accelerator Laboratory