Title Gamma-ray emission properties from mature pulsars in the Galaxy and in the Gould Belt

We study the -ray emission properties of pulsars by using a new self-consistent outer gap model. The outer gap can exist in pulsars older than 1 million yr if the effect of magnetic inclination angle, as well as the average properties of the outer gap, are considered. The mature -ray pulsars, whose ages are between 0.3 and 3 million yr, are able to move up to high Galactic latitude. Moreover, their -ray luminosities are weaker, and their spectra are significantly softer than those of younger -ray pulsars in the Galactic plane. We use a Monte Carlo method to simulate the statistical properties of -ray pulsars in the Galaxy as well as in the Gould Belt. We find that -ray pulsars located at jb j< 5 and jb j> 5 have very different properties. High Galactic latitude -ray pulsars are dominated by mature pulsars with longer periods, weaker fluxes, and softer spectra. If the pulsar birth rates in the Galaxy and the Gould Belt are 10 2 and 2 ; 10 5 yr 1, respectively, there are 42 and 35 radio-quiet -ray pulsars for jb j< 5 and jb j> 5 , respectively. The number of radio-quiet -ray pulsars from theGouldBelt are 2 and 13 for jb j< 5 and jb j> 5 , respectively. We suggest that a good fraction of unidentified EGRET -ray sources may be these radio-quiet -ray pulsars. Furthermore, -ray pulsars located at jb j> 5 satisfy L / L sd, whereas L / L sd for -ray pulsars in the Galactic plane, where 0:6 and 0:3, respectively. Subject headings: gamma rays: theory — pulsars: general — stars: neutron — stars: statistics