The gamma-ray emission region in the FRII Radio Galaxy 3C 111

TL;DR

This study localizes the gamma-ray emission region in the FRII radio galaxy 3C 111, linking gamma-ray activity with multiwavelength outbursts and constraining the emission zone to within 0.1 parsecs from the black hole.

Contribution

First localization of the gamma-ray dissipation zone in an FRII jet using multiwavelength and gamma-ray data analysis.

Findings

Gamma-ray emission coincides with mm, optical, and X-ray outbursts.

The gamma-ray emission region is within 0.1 pc of the black hole.

The emission zone is approximately 0.3 pc from the black hole.

Abstract

The Broad Line Radio Galaxy 3C 111, characterized by a Fanaroff-Riley II (FRII) radio morphology, is one of the sources of the Misaligned Active Galactic Nuclei sample, consisting of Radio Galaxies and Steep Spectrum Radio Quasars, recently detected by the Fermi-Large Area Telescope. Our analysis of the 24-month gamma-ray light curve shows that 3C 111 was only occasionally detected at high energies. It was bright at the end of 2008 and faint, below the Fermi-Large Area Telescope sensitivity threshold, for the rest of the time. A multifrequency campaign of 3C~111, ongoing in the same period, revealed an increase of the mm, optical and X-ray fluxes in 2008 September-November, interpreted by Chatterjee et al. (2011) as due to the passage of a superluminal knot through the jet core. The temporal coincidence of the mm-optical-X-ray outburst with the GeV activity suggests a co-spatiality of the events, allowing, for the first time, the localization of the gamma-ray dissipative zone in a FRII jet. We argue that the GeV photons of 3C 111 are produced in a compact region confined within 0.1 pc and at a distance of about 0.3 pc from the black hole.