Hadronuclear Interactions in Active Galactic Nuclei Jets as the Origin of the Diffuse High-energy Neutrino Background

Abstract

The origin of diffuse high-energy neutrinos from TeV to PeV energies detected by the IceCube Observatory remains a mystery. In our previous work, we have shown that hadronuclear ( p − p ) interactions in active galactic nuclei (AGNs) jets could be important and generate detectable very-high-energy emissions. Here, we further explore these interactions in the AGN jets based on their luminosity function. The diffuse neutrino flux and corresponding γ -ray flux have been calculated and compared with observational data. In our modeling, two beaming patterns are considered separately. To make sure that the corresponding γ -ray flux does not overshoot the diffuse γ -ray background, we find that if the neutrino production region in a jet is opaque to γ -rays, p − p interactions in AGN jets with a small viewing angle (the blazar case) are able to interpret the PeV neutrino background. Similarly, AGN jets with a large viewing angle (the radio galaxy case) may interpret the TeV neutrino background. While, if the neutrino production region is transparent to γ -rays, only blazars have the potential to interpret the diffuse neutrino background around the PeV band. Some caveats are also discussed.

Keywords

• Active galactic nuclei
• Gamma-ray sources
• High energy astrophysics
• Neutrino astronomy