MAGIC observation of an exceptional TeV gamma-ray flare in the active galaxy IC 310

The AGN IC 310 has been identified as a gamma-ray emitter based on observations at very high energies (VHE,E>100 GeV) with the MAGIC telescopes. Despite IC 310 having been classified as a radio galaxy with the jet observed at an angle>10 degrees, it exhibits a mixture of multiwavelength properties of a radio galaxy and a blazar, possibly making it a transitional object. On the night of 12/13th of November 2012 the MAGIC telescopes observed a series of strong outbursts from the direction of IC 310 with flux-doubling time scales faster than 5 min and a peculiar spectrum spreading over two orders of magnitude. Such fast variability constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole. In fact, the measurement challenges the shock acceleration models, commonly used in explanation of gamma-ray radiation from active galaxies. We show that this emission can be associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the jet.