Gamma-ray blazar in northern sky

An analysis incorporating the radio and X-ray properties and the gamma-ray source localization is used to gauge the reliability of associations and to search for counterparts of previously unidentified EGRET sources. Above |b|=10{deg}, where the classification is complete, we find that 70% of the northern EGRET sources have counterparts similar to the bright EGRET blazars.

For several of these we identify known blazar counterparts more likely than the earlier proposed 3EG association; for ~20 we have new identifications. Spectroscopic confirmation of these candidates is in progress, and we have found flat-spectrum radio quasars and BL Lacertae counterparts with redshifts as high as 4. We also find strong evidence for a set of 28 objects with no plausible counterpart like the known EGRET blazars.