Galactic Gamma-Ray Sources

The EGRET telescope has detected over 200 γ-ray sources above 100 MeV, but many remain unidentified because of their poor localization or their faintness at lower energies. Multi-wavelength searches have proved successful at finding interesting blazar and pulsar counterparts at high latitudes, but rarely in the Galactic plane because of confusion. Yet, their spatial distribution and time variability strongly suggest that several populations are involved in different parts of the Galaxy, along the Gould Belt, in regions of star formation, in the inner spiral arms, and around the Galactic bulge. They imply a much larger variety of potential emitters than just pulsars and supernova remnants, but their nature eludes us. Various possibilities are discussed with the observa-tional evidence. Promising identifications with individual objects are also reviewed.