2003ApJ...592L...5K

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.