Astrophysical Gamma-ray and Neutrino Production Following from the Physics of Photon-Nucleon Interactions

TL;DR

This paper provides a comprehensive analysis of photon-nucleon interactions, emphasizing pion and meson production, and their implications for astrophysical gamma-ray and neutrino sources, based on recent empirical data.

Contribution

It offers an updated theoretical and experimental framework for photon-nucleon interactions, highlighting the dominance of the Delta(1232) resonance and the limited role of other mesons in astrophysical neutrino and gamma-ray production.

Findings

Photoproduction with helium yields about 10% of pions compared to protons.

The Delta(1232) resonance dominates neutrino and gamma-ray production.

Nucleon resonances at 1400 GeV can contribute up to 20% to neutrino flux.

Abstract

The aim of this paper is to present a more complete consideration of the theoretical concepts and experimental aspects of the physics of photoproduction interactions involving nuclei. This treatment is based in large part on the most recent and extensive empirical data on particle photoproduction interactions with protons. The implications of photoproduction involving helium nuclei are also treated and compared with photoproduction involving protons. It is found that photoproduction interactions with helium nuclei produce approximately 10% of the number of pions as compared with photoproduction interactions involving protons in astrophysical sources, assuming the cosmological abundance of He. In addition to the production of pions, we also demonstrate the relative effect of excited nucleon p-pi and p-2pi resonances and rho, eta, omega, and K meson production and decay channels that result in neutrino and gamma-ray production. The production of mesons other than pions is shown not to be significant for calculations of astrophysical gamma-ray and neutrino production. It is further shown that, for astrophysical purposes, the Delta(1232) resonance channel clearly dominates. However, a blend of nucleon resonances at 1400 GeV can contribute as much as 20% to the neutrino flux.