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

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 gamma-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 gamma-ray flux does not overshoot the diffuse gamma-ray background, we find that if the neutrino production region in a jet is opaque to gamma-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 gamma-rays, only blazars have the potential to interpret the diffuse neutrino background around the PeV band. Some caveats are also discussed.