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

• Published in: The Astrophysical journal 2024-08, Vol.971 (2), p.146
• Main Authors: Xue, Rui, Wang, Ze-Rui, Joshi, Jagdish C., Li, Wei-Jian
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Blazars; Fluctuations; Galaxies; Gamma ray astronomy; Gamma rays; Gamma-ray sources; High energy astronomy; High energy astrophysics; Jets; Luminosity; Neutrino astronomy; Neutrinos; Radio galaxies; Viewing
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad5fe9

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.