Evidence for Shocks as the Origin of Gamma-Ray Flares in Blazars
  We present centimeter-band total flux density and linear polarization light curves illustrating the signature of shocks during radio band outbursts associated in time with gamma-ray flares detected by the Fermi LAT. The general characteristics of the spectral evolution during these events is well-explained by new radiative transfer simulations incorporating propagating oblique shocks and assuming an initially turbulent magnetic field. This finding supports the idea that oblique shocks in the jet are a viable explanation for activity from the radio to the gamma-ray band in at least some gamma-ray flares. 
M. F. Aller, P. A. Hughes, H. D. Aller, A. P. Marscher, S. G. Jorstad,   T. Hovatta, M. C. Aller
astro-ph.HE