Gamma-ray emission of hot astrophysical plasmas

TL;DR

This paper investigates gamma-ray emissions from extremely hot astrophysical plasmas, modeling their nuclear reactions and emission signatures, and analyzing how particle distribution deviations affect gamma-ray emissivity.

Contribution

It provides detailed nuclear reaction modeling and analytical formulas for gamma-ray production in hot plasmas, including effects of non-Maxwellian particle distributions.

Findings

Computed the chemical evolution of hot plasmas using a nuclear reaction network.

Derived analytical expressions for $^0$-meson production and gamma-ray emissivity.

Analyzed the impact of high-energy tail deviations on gamma-ray emission.

Abstract

Very hot plasmas with ion temperature exceeding $10^{10}$ K can be formed in certain astrophysical environments. The distinct radiation signature of such plasmas is the $\gamma$-ray emission dominated by the prompt de-excitation nuclear lines and $\pi^0$-decay $\gamma$-rays. Using a large nuclear reaction network, we compute the time evolution of the chemical composition of such hot plasmas and their $\gamma$-ray line emissivity. At higher energies, we provide simple but accurate analytical presentations for the $\pi^0$-meson production rate and the corresponding $\pi^0\to2\gamma$ emissivity derived for the Maxwellian distribution of protons. We discuss the impact of the possible deviation of the high energy tail of the particle distribution function from the "nominal" Maxwellian distribution on the plasma $\gamma$-ray emissivity.