Could the Unidentified EGRET Sources in the Gould Belt be of Pulsar Origin

摘要

We explore the possibility, within the polar cap model, that at least some of the recently identified new population of Energetic Gamma-Ray Experiment Telescope (EGRET) sources in the Gould Belt sources are gamma-ray pulsars, viewed at large angles to the magnetic axis, such that the line-of-sight misses both the bright gamma-ray double cone and the radio beam. We estimate that the detectability of such off-beam gamma-ray sources is about a factor of 4-5 times higher than that of the on-beam sources. The off-beam gamma-ray pulsars also have a faint, soft nature, which is consistent with the observed properties of the Gould Belt sources. We conclude that at least some of the middle latitude sources might be such off-beam gamma-ray pulsars if they are indeed in the Gould Belt.