High Energy Radiation Generated at Boundary Shear Layers of Relativistic Jets

A simple model of cosmic ray electron acceleration at the jet boundary (Ostrowski 2000) yields a power-law particle energy distribution of ultrarelativistic electrons with an energy cut-off growing with time and finally, a growing particle bump at the energy, where energy gains equal radiation losses. For such electron distribution, in tens-of-kpc scale jets, we derived the observed time varying spectra of synchrotron and inverse-Compton radiation, including comptonization of synchrotron and cosmic microwave background photons. Slowly varying spectral index along the jet in the `low-frequency' spectral range is a natural consequence of boundary layer acceleration. Variations of the high energy bump of the electron distribution can give rise to anomalous behaviour in X-ray band in comparison to the lower frequencies.