The relationship between gamma emission and radio flares in AGN

A comparison between Phase 1 EGRET data and Metsahovi total flux density monitoring at 22 GHz and 37 GHz shows that gamma-rays are likely to be detected only in quasars with high optical polarization, and even them only during the initial stages of a high radio frequency outburst. Other types of sources, including BL Lacs, are rarely detected. There also appears to be a correlation between the radio flare strength, rapidity, and the detected gamma-ray flux. Taken together, these results indicate that gamma-rays are produced by the synchrotron self-Compton mechanism in the shocked regions of the jet, with both the relativistic electrons and the seed photons originating in the same shock far away from the core and the accretion disk.