Let there be neutrons! Hadronic photoproduction from a large flux of high-energy photons

TL;DR

This paper explores how high-energy photons in astrophysical environments can induce reactions on baryons, producing neutrons and enabling neutron-capture nucleosynthesis in cosmic settings like gamma-ray bursts.

Contribution

It introduces a novel mechanism for neutron production via photohadronic interactions in high-energy astrophysical environments, expanding understanding of nucleosynthesis processes.

Findings

Neutrons can be generated in situ in astrophysical jets.

Photohadronic reactions can produce neutrons even from baryon-free material.

This process may influence neutron-capture nucleosynthesis in cosmic phenomena.

Abstract

We propose that neutrons may be generated in high-energy, high-flux photon environments via photo-induced reactions on pre-existing baryons. These photohadronic interactions are expected to occur in astrophysical jets and surrounding material. Historically, these reactions have been attributed to the production of high-energy cosmic rays and neutrinos. We estimate the photoproduction off of protons in the context of gamma-ray bursts, where it is expected there will be sufficient baryonic material that may be encompassing or entrained in the jet. We show that typical stellar baryonic material, even material completely devoid of neutrons, can become inundated with neutrons in situ via hadronic photoproduction. Consequently, this mechanism provides a means for collapsars and other astrophysical sites containing substantial flux of high-energy photons to be favorable for neutron-capture nucleosynthesis.