Gamma-ray blazars near equipartition and the origin of the GeV spectral break in 3C 454.3

摘要

Observations performed with the Fermi-LAT telescope have revealed thepresence of a spectral break in the GeV spectrum of flat-spectrum radio quasars(FSRQs) and other low- and intermediate-synchrotron peaked blazars. We proposethat this feature can be explained by Compton scattering of broad-line region(BLR) photons by a non-thermal population of electrons described by alog-parabolic function. We consider in particular a scenario in which theenergy densities of particles, magnetic field, and soft photons in the emittingregion are close to equipartition. We show that this model can satisfactorilyaccount for the overall spectral energy distribution of the FSRQ 3C 454.3,reproducing the GeV spectal cutoff due to Klein-Nishina effects and a curvingelectron distribution.