High-energy neutrinos from the vicinity of the supermassive black hole in NGC 1068

Abstract

We present a comprehensive multi-messenger study of NGC 1068, the prototype Seyfert II galaxy associated with high-energy neutrinos following a detection by the IceCube Neutrino Observatory. Various aspects of the source, including its nuclear activity, jet, outflow and starburst region, are analysed in detail using a multi-wavelength approach and relevant luminosities are derived. We then explore its γ-ray and neutrino emissions and investigate the potential mechanisms underlying these phenomena and their relations with the different astrophysical components to try to understand which is responsible for the IceCube neutrinos. By first using simple order-of-magnitude arguments and then applying specific theoretical models, we infer that only the region close to the accretion disk around the supermassive black hole has the right density of both the X-ray photons needed to provide the targets for protons to sustain neutrino production and the optical/infrared photons required to absorb the associated, but unobserved, γ-rays. We conclude by highlighting ongoing efforts to constrain a possible broad connection between neutrinos and active galactic nuclei, as well as future synergies between astronomical and neutrino facilities. Observations of the galaxy NGC 1068 in different wavebands are brought together in a multi-messenger case study, exploring the potential origin and mechanisms responsible for the recently detected neutrino emission from this source.