Obscured flat spectrum radio AGN as sources of high-energy neutrinos

TL;DR

This paper investigates a specific subclass of obscured, jet-aligned AGN as potential sources of high-energy cosmic neutrinos, introducing a method to estimate their surrounding matter density and identify promising neutrino-emitting candidates.

Contribution

It presents a novel method to determine the obscuring medium's density in AGN and applies it to select low-redshift radio galaxies likely to produce high-energy neutrinos.

Findings

Identified a sample of AGN with high potential for neutrino production.

Developed a method linking X-ray attenuation to surrounding matter density.

Provided a list of candidate sources for future neutrino detection studies.

Abstract

Active Galactic Nuclei (AGN) are believed to be one of the main source candidates for the high-energy (TeV-PeV) cosmic neutrino flux recently discovered by the IceCube neutrino observatory. Nevertheless, several correlation studies between AGN and the cosmic neutrinos detected by IceCube show no significance. Therefore, in this article we consider a specific sub-class of AGN for which an increased neutrino production is expected. This sub-class contains AGN for which their high-energy jet is pointing toward Earth. Furthermore, we impose the condition that the jet is obscured by gas or dust surrounding the AGN. A method is presented to determine the total column density of the obscuring medium, which is probed by determining the relative X-ray attenuation with respect to the radio flux as obtained from the AGN spectrum. The total column density allows us to probe the interaction of the jet with the surrounding matter which leads to additional neutrino production. Finally, starting from two different source catalogs, this method is applied to specify a sample of low redshift radio galaxies for which an increased neutrino production is expected.