The Electron Spectrum in 3C 279 and the Observed Emission Spectrum

Abstract

The emission mechanisms of the blazar 3C 279 are studied by solving the kinetic equations of electrons and photons in a relativistically moving blob. The γ-ray spectral energy distribution (SED) is fitted by inverse Compton scattering of external photons. The bulk Lorentz factor of the emitting blob is found to be ~25, and the magnetic field is found to be ~0.3 G. GeV γ-rays are well explained by inefficiently cooled electrons because of the Klein-Nishina effects. The electron spectrum is not a broken power law with a steeper spectrum above a break energy, which is often used to fit the observed SED. The kinetic energy density of the nonthermal electrons dominates the magnetic energy density; this result is qualitatively the same as that for TeV blazars such as Mrk 421 and Mrk 501. The γ-ray luminosity of 3C 279 is often observed to increase rapidly. We show that one of the better sampled γ-ray flares can be explained by the internal shock model.