Discovery of a new population of high-energy gamma-ray sources in the Milky Way

One of the great mysteries of the high-energy gamma-ray sky is the group of similar to 170 unidentified point sources(1,2) found along the Galactic pl ane. They are more numerous than all other high-energy gamma-ray sources co mbined and, despite 20 years of effort, no clear counterparts have been fou nd at other wavelengths. Here we report a new population of such objects. A cluster of similar to 20 faint sources appears north of the Galactic Centr e, which is part of a broader class of faint objects at mid-latitudes. In a ddition, we show in a model-independent way that the mid-latitude sources a re distinct from the population of bright unidentified sources along the Ga lactic plane. The distribution on the sky indicates that the faint mid-lati tude sources are associated with the Gould belt(3,4) of massive stars and g as clouds at similar to 600 light years distance, as has been previously su ggested(5).