Insights into the particle acceleration of a peculiar gamma -ray radio galaxy IC 310

TL;DR

This paper investigates the gamma-ray emission from IC 310, a peculiar radio galaxy with blazar-like properties, revealing rapid variability and proposing pulsar-like acceleration as the emission mechanism.

Contribution

It introduces a novel explanation for IC 310's gamma-ray emission involving pulsar-like acceleration, challenging traditional shock acceleration models.

Findings

Fast variability constrains emission region size to <20% of black hole's gravitational radius

Observed spectrum spans over 2 orders of magnitude

Emission likely caused by pulsar-like particle acceleration

Abstract

IC 310 has recently been identified as a gamma-ray emitter based on observations at GeV energies with Fermi-LAT and 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 violent outbursts from the direction of IC 310 with flux-doubling time scales faster than 5 min and a peculiar spectrum spreading over 2 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, challenging the shock acceleration models, commonly used in explanation of gamma-ray radiation from active galaxies. Here we will 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.