Comptonization of infrared radiation from hot dust by relativistic jets inquasars

We demonstrate the importance of near-infrared radiation from hot dust for Compton cooling of electrons/positrons in quasar jets. In our model, we ass ume that the nonthermal radiation spectra observed in optically violent var iable (OVV) quasars are produced by relativistic electrons/positrons accele rated in thin shells that propagate down the jet with relativistic speeds. We show that the Comptonization of the near-IR flux is likely to dominate t he radiative output of OVV quasars in the energy range from tens of keV up to hundreds of MeV, where it exceeds that produced by Comptonization of the UV radiation reprocessed and rescattered in the broad emission line (BEL) region. The main reason for this lies in the fact that the jet encounters t he ambient IR radiation over a relatively large distance as compared to the distance where the energy density of the BEL light peaks. In the soft to m id-energy X-ray band, the spectral component resulting from Comptonization of the near-IR radiation joins smoothly with the synchrotron self-Compton c omponent, which may be responsible for the soft X-ray flux. At the highest observed gamma -ray energies, in the GeV range, Comptonization of broad emi ssion lines dominates over other components.