Soft gamma-rays from blazars

The broad-band energy distributions of those AGN which owe their luminosity to non-thermal radiation processes show two broad bumps. The lower-energy bump is due to synchrotron emission and extends into the soft X-ray regime in most objects. The Compton-scattered radiation can be observed in the gam ma-ray range and extends well into the TeV regime explored by ground-based Cerenkov telescopes. A multi-frequency campaign on Mrk 501 in 1997, involvi ng simultaneous TeV, X-ray, and lower energies not only found that the sync hrotron emission extends above 100 keV but also demonstrated that the hard X-ray spectra of rising flares reach the maximum hardness for synchrotron e mission.