Generation possibility of gamma-ray glows induced by photonuclear reactions

TL;DR

This paper explores how photonuclear reactions triggered by terrestrial gamma-ray flashes can produce chain reactions that sustain gamma-ray glows, providing insights into their potential common origin and the mechanisms involved.

Contribution

It demonstrates that TGF byproducts can initiate chain reactions lasting for gamma-ray glow timescales, linking TGFs and TGEs through photonuclear processes.

Findings

Chain reactions by TGF byproducts can last for gamma-ray glow durations.

Photonuclear reactions can produce energetic particles serving as RREA seeds.

Potential common mechanism for TGFs and TGEs via photonuclear processes.

Abstract

Relativistic runaway electron avalanches (RREAs) imply a large multiplication of high energy electrons (~1 MeV). Two factors are necessary for this phenomenon: a high electric field sustained over a large distance and an energetic particle to serve as a seed. The former sustains particle energies as they keep colliding and lose energy randomly, and the latter serves as a multiplication starting point that promotes avalanches. RREA is usually connected to both terrestrial gamma-ray flashes (TGFs) and gamma-ray glows (also known as Thunderstorm Ground Enhancement (TGE) when detected at ground level) as possible generation mechanism of both events, but the current knowledge does not provide a clear relationship between these events (TGF and TGE), beyond their possible common source mechanism, still as they have different characteristics. In particular, their timescales differ by several orders of magnitude. This work shows that chain reactions by TGF byproducts can continue for the timescale of gamma-ray glows and even provide energetic particles as seeds for RREAs of gamma-ray glows.