Off-beam gamma-ray pulsars and unidentified EGRET sources in the Gould Belt

Citation
Ak. Harding et B. Zhang, Off-beam gamma-ray pulsars and unidentified EGRET sources in the Gould Belt, ASTROPHYS J, 548(1), 2001, pp. L37-L40
Citations number
13
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004-637X → ACNP
Volume
548
Issue
1
Year of publication
2001
Part
2
Pages
L37 - L40
Database
ISI
SICI code
0004-637X(20010210)548:1<L37:OGPAUE>2.0.ZU;2-1
Abstract
We investigate whether gamma-ray pulsars viewed at a large angle to the neu tron star magnetic pole could contribute to the new population of Galactic unidentified EGRET sources associated with the Gould Belt. The faint, soft nature of these sources is distinctly different from both the properties of unidentified EGRET sources along the Galactic plane and the properties of the known gamma-ray pulsars. We explore the possibility, within the polar c ap model, that some of these sources are emission from pulsars seen at line s of sight that miss both the bright gamma-ray cone beams and the radio bea m. The off-beam gamma rays come from high-altitude curvature emission of pr imary particles, are radiated over a large solid angle and have a much soft er spectrum than that of the main beams. We estimate that the relative dete ctability of such off-beam emission is about a factor of 4-5 higher than th at of the on-beam emission. At least some of the radio-quiet Gould Belt sou rces detected by EGRET could therefore be such off-beam gamma-ray pulsars. The Gamma-ray Large Area Space Telescope should be able to detect pulsation s in most of these sources.