On the relative importance of hadronic emission processes along the jet axis of Active Galactic Nuclei

TL;DR

This paper develops a detailed model of high-energy particle emissions in AGN jets, demonstrating how hadronic processes can produce neutrino flares with minimal gamma-ray emission, relevant for understanding sources like TXS 0506+056.

Contribution

It introduces a space and time-resolved model of particle emission in AGN jets using an adapted CRPropa framework, focusing on hadronic interactions and neutrino production.

Findings

PeV-neutrino flares can be produced mainly by photo-hadronic interactions.

Gamma-ray attenuation occurs around 10 TeV due to ambient photon fields.

Model can be fitted to specific AGN flare scenarios in future work.

Abstract

With the coincident detection of a gamma-ray flare and a neutrino from the blazar TXS 0506+056, Active Galactic Nuclei (AGN) have been put into focus as possible sources of the diffuse neutrino flux. We present a space and time-resolved model of the high-energy particle emission of a plasmoid assumed to travel along the axis of an AGN jet at relativistic speed. This was achieved by modifying the publicly available CRPropa (version 3.1+) propagation framework which in our work is capable of being applied to source physics on sub-kpc scales. The propagation of a population of primary protons is modelled in a purely turbulent magnetic field and we take into account interactions of these protons with photons scattered from the accretion disc, synchrotron radiation emitted by ambient relativistic electrons, as well with themselves and with other ambient matter. Our model produces a PeV-neutrino flare caused mainly by photo-hadronic interactions of primaries with the accretion disc field. Secondary high-energy gamma-rays partly attenuate with the ambient photon fields whose combined optical depths achieve their minimal opacity for photons of around 10 TeV. Thus, our model is well capable of producing neutrino flares with a significantly reduced emission of gamma-rays in jets with a hadronic jet component which in the future can be fit to specific AGN flare scenarios.