SIMBAD references

The flat-spectrum radio quasar PKS 1222+216 (4C+21.35, z=0.432) was detected in the very high energy γ-ray band by MAGIC during a highly active γ-ray phase following an alert by the Large Area Telescope (LAT) onboard Fermi. Its relatively hard spectrum (70-400 GeV photon index Γ=2.7±0.3) without a cut off, together with its observed variability on a timescale of ∼10 min challenges standard emission models. In particular, if the emission originates in a portion of the relativistic jet located inside the broad line region (BLR), severe absorption of γ rays above a few tens of GeV is expected to be caused by the γγ->e^± process. These observations therefore imply that there is a very compact (R_b∼5x10¹⁴cm) and rapidly moving blob located far beyond the BLR radius (to avoid the gamma-ray absorption through pair production) that is responsible for the rapidly varying high energy flux. However, the long-term (day-week) coherent evolution of the GeV flux recorded by LAT indicates that there could also be a substantial contribution from another, larger emission region. We model the spectral energy distribution of PKS 1222+216 during the epoch of the MAGIC detection assuming three different scenarios, namely: (1) a one-zone model considering only the emission from a compact blob outside the BLR; (2) a two-zone model consisting of a compact blob plus an emitting region encompassing the whole jet cross-section located outside the BLR; and (3) a two-zone model with the jet emitting region inside the BLR. In all cases we find that the high-energy emission from the compact blob is dominated by the inverse Compton scattering of the infrared thermal radiation of the dusty torus. Furthermore, both regions are matter-dominated, with the Poynting flux providing a negligible contribution to the total jet power. These results do not support models in which the compact blob is the result of reconnection events inside the jet or ``needles'' of high-energy electrons accelerated close to the BH. The observational framework and our radiative models might instead be compatible with scenarios in which the jet is re-collimated and focussed at large distances from the central BH.