The populations of EGRET sources off the Galactic plane

I. A. Grenier
Université Paris VII and CEA Saclay, France

The sources observed at |b| > 5 deg are clearly distinct from the low-latitude sources in their logN-logS and average spectral index (Gehrels et al., 2000) Their combined temporal, spatial, and spectral characteristics further indicates the existence of two populations, both of Galactic origin, in addition to a score of extragalactic sources. It is proposed 1) that the harder, more persistent sources, which are spatially correlated with the Gould Belt, are Myr-old, nearby pulsars born in the starburst belt; 2) that the softer, more variable sources correspond to a population of old, but luminous Galactic sources with a large scale height above the plane.


isabelle.grenier@cea.fr