EGRET high-energy gamma-ray pulsar studies .3. A survey

The 3.5 yr database of the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory has been surveyed for gamma-ray emission from all known spin-powered pulsars. Using contemporaneous timing solutions, upper limits on pulsed emission were obtained for 350 pulsars. Limits to unpulsed gamma radiation were obtained for all cataloged pulsars. No new pulsar detections have been found, although there is evidence for localized excesses at the positions of a few of these pulsars. No significant correlation was, however, found between E/d(2) and the sources of such unpulsed excesses. A number of models predict the relative gamma-ray luminosity from pulsars as a function of measurable pulsar parameters. By fitting these models to the six detected pulsars above 100 MeV, the functional form of models are tested, and we find that the luminosity does not scale with the pulsar parameters as predicted. Furthermore, some flux upper limits derived here appear to contradict the model predictions. This seems to indicate that the current models of gamma-ray pulsars are still incomplete.