THE UV DRAG ON HADRONIC HOT JETS AS THE ORIGIN OF X-RAY-IRRADIATION IN AGN

In this paper I calculate the anisotropic flux of cascade radiation pr oduced by an isotropic distribution of highly relativistic protons imm ersed in the photon field of a spatially separated point source. Most radiation is produced towards the source of the target photons. An ast rophysical application of this result is X-ray irradiation of AGN accr etion disks by highly dissipative nuclear jets. Low Mach number jets c onvert a large fraction of their kinetic power into relativistic parti cles via resonance with MHD turbulence. Consequently, these jets do no t show up as radio jets on large scales. Protons can easily reach high energies by stochastic acceleration in the turbulent jet plasma, wher eas severe energy losses make it very difficult for the electrons to b e accelerated at all. Proton acceleration saturates at the threshold e nergy for photo-production of secondary particles in the radiation fie ld of the inner accretion disk. The energetic secondaries initiate an anisotropic electromagnetic cascade. The backward cascade flux is repr ocessed by the underlying accretion disk. The small fraction of cascad e gamma-rays emitted in the forward direction is consistent with gamma -ray flux limits for Seyfert galaxies and with the spectrum of the dif fuse cosmic photon flux at high energies.