1211.0296 (Dimitrios Giannios)

Reconnection-driven plasmoids in blazars: fast flares on a slow envelope    [PDF]

Dimitrios Giannios

Minute-timescale TeV flares have been observed in several blazars. The fast flaring requires compact regions in the jet that boost their emission towards the observer at an extreme Doppler factor of delta>50. For TeV photons to avoid annihilation in the broad line region of PKS 1222+216, the flares must come from large (pc) scales challenging most models proposed to explain them. Here we elaborate on the magnetic reconnection minijet model for the blazar flaring, focusing on the inherently time-dependent aspects of the process of magnetic reconnection. I argue that, for the physical conditions prevailing in blazar jets, the reconnection layer fragments leading to the formation a large number of plasmoids. Occasionally a plasmoid grows to become a large, "monster" plasmoid. I show that radiation emitted from the reconnection event can account for the observed "envelope" of \sim day-long blazar activity while radiation from monster plasmoids can power the fastest TeV flares. The model is applied to several blazars with observed fast flaring. The inferred distance of the dissipation zone is R_diss \sim0.3-1 pc. The required magnetization of the jet at this distance is modest: sigma \sim a few.

View original: http://arxiv.org/abs/1211.0296