Fermi Unassociated Sources in the MeerKAT Absorption Line Survey
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-...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ada1cf |
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| author | Morgan Himes Preshanth Jagannathan Dale A. Frail Frank Schinzel Neeraj Gupta S. A. Balashev F. Combes P. P. Deka H.-R. Klöckner E. Momjian J. D. Wagenveld |
| author_facet | Morgan Himes Preshanth Jagannathan Dale A. Frail Frank Schinzel Neeraj Gupta S. A. Balashev F. Combes P. P. Deka H.-R. Klöckner E. Momjian J. D. Wagenveld |
| author_sort | Morgan Himes |
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| description | 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. |
| format | Article |
| id | doaj-art-621672dcd0bc4139805e303833ce54fc |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-621672dcd0bc4139805e303833ce54fc2025-02-05T13:52:40ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198018110.3847/1538-4357/ada1cfFermi Unassociated Sources in the MeerKAT Absorption Line SurveyMorgan Himes0https://orcid.org/0009-0004-1469-9550Preshanth Jagannathan1https://orcid.org/0000-0002-5825-9635Dale A. Frail2https://orcid.org/0009-0008-7604-003XFrank Schinzel3https://orcid.org/0000-0001-6672-128XNeeraj Gupta4https://orcid.org/0000-0001-7547-4241S. A. Balashev5https://orcid.org/0000-0002-3814-9666F. Combes6https://orcid.org/0000-0003-2658-7893P. P. Deka7https://orcid.org/0000-0002-9931-1313H.-R. Klöckner8https://orcid.org/0000-0002-0648-2704E. Momjian9https://orcid.org/0000-0003-3168-5922J. D. Wagenveld10https://orcid.org/0000-0003-1321-0886National Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USA; University of Florida , Gainesville, FL 32611, USANational Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USANational Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USANational Radio Astronomy Observatory , 1003 Lopezville Road, Socorro, NM 87801, USAInter University Centre for Astronomy and Astrophysics , Pune, Maharashtra 411007, IndiaIndependent ResearcherObservatoire de Paris, Collège de France, PSL University, Sorbonne University , CNRS, LERMA, Paris, FranceInter University Centre for Astronomy and Astrophysics , Post Bag 4, Ganeshkhind, Pune 411 007, IndiaMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, GermanyNational Radio Astronomy Observatory , Socorro, NM 87801, USAMax-Planck-Institut für Radioastronomie , Auf dem Hügel 69, D-53121 Bonn, GermanyOver 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.https://doi.org/10.3847/1538-4357/ada1cfMillisecond pulsarsPulsarsGamma-ray sourcesDiscrete radio sourcesRadio astrometryRadio galaxies |
| spellingShingle | Morgan Himes Preshanth Jagannathan Dale A. Frail Frank Schinzel Neeraj Gupta S. A. Balashev F. Combes P. P. Deka H.-R. Klöckner E. Momjian J. D. Wagenveld Fermi Unassociated Sources in the MeerKAT Absorption Line Survey The Astrophysical Journal Millisecond pulsars Pulsars Gamma-ray sources Discrete radio sources Radio astrometry Radio galaxies |
| title | Fermi Unassociated Sources in the MeerKAT Absorption Line Survey |
| title_full | Fermi Unassociated Sources in the MeerKAT Absorption Line Survey |
| title_fullStr | Fermi Unassociated Sources in the MeerKAT Absorption Line Survey |
| title_full_unstemmed | Fermi Unassociated Sources in the MeerKAT Absorption Line Survey |
| title_short | Fermi Unassociated Sources in the MeerKAT Absorption Line Survey |
| title_sort | fermi unassociated sources in the meerkat absorption line survey |
| topic | Millisecond pulsars Pulsars Gamma-ray sources Discrete radio sources Radio astrometry Radio galaxies |
| url | https://doi.org/10.3847/1538-4357/ada1cf |
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