Name of the Speaker(s):Marek Sikora
Institution: N. Copernicus Astronomical Center Polish Academy of Sciences
Title of the communication: Do we have the theory of gamma-ray blazars?
Preliminary abstract (12 lines max.): We show that the high energy spectra of gamma-ray loud blazars cannot be explained by any simple version of existing models. The ``differential'' pair models fail to reproduce flat X-ray spectra, the hadronic models fails to reproduce steep gamma-ray spectra, the synchrotron-self-Compton models require too low magnetic energy densities, and the external-radiation-Compton models predict too much soft X-rays. We argue that soft X-ray excesses, which are predicted by us to accompany hard X-ray and gamma-ray spectra in all models, can be avoided only in a case of efficient collective plasma processes keeping electrons at relativistic temperatures, or negligible pair production in a jet.