PAIR BREMSSTRAHLUNG RADIATION FROM RELATIVISTIC JETS IN GAMMA-RAY BLAZARS

The yield of e(-)-e(+)- and e(-)-e(-)-bremsstrah-lung in the hard X-ray and gamma-ray regime from leptonic jets in active galactic nuclei is calculated. We argue that in the case of ultrarelativistic jets where the intrinsic particle spectra have lower cutoffs greater than or similar to 5 the contribution of e(-)-e(+)- and e(-)-e(-)-bremsstrahlung overwhelms the yield of pair annihilation radiation which poses severe constraints on models trying to explain spectral bumps at MeV energies observed in the gamma-ray spectra of many AGNs by a broadened, blue shifted annihilation line from an ultrarelativistic pair plasma. It is demonstrated that bremsstrahlung emission from a power-law distribution of relativistic particles could as well be responsible for spectral breaks Delta alpha greater than or equal to 0.5 at MeV energies with the instantaneous photon spectra having a flat shape (alpha approximate to 1.1 in photon number spectrum) at photon energies well below the break.