ON THE NATURE OF THE UNIDENTIFIED EGRET SOURCES: ARE THEY GEMINGA-LIKE PULSARS?

摘要

Observations with the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory show more than 30 unidentified gamma-ray sources concentrated along the Galactic plane. Based on their spatial distribution, the typical distances of the sources are found to be between 1.2 and 6 kpc. Luminosity estimates made using the estimated distances of the sources and their observed gamma-ray fluxes lie in the range (0.7-16.7) x 10~(35) ergs s~(-1). These values, on the average, appear to be higher than the luminosities of the gamma-ray pulsars observed by EGRET. The luminosity estimates indicate that the low-latitude unidentified EGRET sources cannot be explained as a group of older, low-luminosity pulsars like Geminga, although the high-latitude sources may be candidates.