An image-based search for pulsars among Fermi unassociated LAT sources

Abstract We describe an image-based method that uses two radio criteria, compactness, and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope al...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2018-03, Vol.475 (1), p.942-954
Main Authors: Frail, D A, Ray, P S, Mooley, K P, Hancock, P, Burnett, T H, Jagannathan, P, Ferrara, E C, Intema, H T, de Gasperin, F, Demorest, P B, Stovall, K, McKinnon, M M
Format: Article
Language:English
Subjects:
Criteria
Gamma rays
Pulsars
Radio telescopes
Searching
Sky surveys (astronomy)
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Summary:Abstract We describe an image-based method that uses two radio criteria, compactness, and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope all-sky survey at 150 MHz (TGSS ADR1) found within the error ellipses of unassociated sources from the 3FGL catalogue and a preliminary source list based on 7 yr of LAT data. After follow-up interferometric observations to identify extended or variable sources, a list of 16 compact, steep-spectrum candidates is generated. An ongoing search for pulsations in these candidates, in gamma rays and radio, has found 6 ms pulsars and one normal pulsar. A comparison of this method with existing selection criteria based on gamma-ray spectral and variability properties suggests that the pulsar discovery space using Fermi may be larger than previously thought. Radio imaging is a hitherto underutilized source selection method that can be used, as with other multiwavelength techniques, in the search for Fermi pulsars.
ISSN:0035-8711
1365-2966
DOI:10.1093/mnras/stx3281