1996A&AS..120C.481S

It is argued that the high-energy X-ray and γ-ray emission from flaring blazars is beamed radiation from the relativistic jet supporting the relativistic beaming hypothesis and the unified scenario for active galactic nuclei (AGNs). Most probably the high-energy emission results from the inverse Compton scattering by relativistic electrons and positrons in the jet of radiation originating external to the jet plus intrinsic jet pair annihilation and bremsstrahlung radiation. Direct γ-ray production by energetic hadrons is not important for the flaring phase in γ-ray blazars, but the acceleration of energetic hadrons during the quiescent phase of AGNs may be relevant as the source of secondary electrons and positrons through photo-pair and photo-pion production. The start of the γ-ray flare is accompanied by the emergence of a new superluminal jet component. Combining time-correlated flux measurements at optical and γ-ray frequencies with contemporaneous VLBI measurements of the apparent transverse speed of the emerging jet component, one finds that a simple diagram relates different classes of radio-loud AGNs and makes definite predictions for the multiwavelength observations of these sources. If an equipartition parameter remains constant between episodes of plasma ejection, then multiple observations of individual sources can in principle determine cosmological parameters