Heavy Axions Can Disrupt $\gamma$-ray Bursts

TL;DR

This paper explores how heavy axion-like particles (ALPs) produced in gamma-ray burst fireballs can escape, disrupting the fireball process and dimming the bursts, which allows setting new constraints on ALP properties.

Contribution

It introduces a novel mechanism where heavy ALPs disrupt GRB fireballs, leading to new bounds on ALP-photon coupling in the 200 MeV to 5 GeV mass range.

Findings

Heavy ALPs can carry away energy from GRB fireballs.

Disruption of fireballs by ALPs dims gamma-ray bursts.

New bounds on ALP-photon coupling are established.

Abstract

Axion-like particles (ALPs) can be produced in the hot dense plasma of fireballs that develop in the initial stage of $\gamma$-ray burst (GRB) outflows. They can transport an enormous amount of energy away from the jet by propagating out of the fireball. The photons produced by the eventual decay of such ALPs do not reach a sufficient density to re-thermalize through pair production, preventing fireball re-emergence. Thus, the production of heavy ALPs disrupts the fireball and dims GRBs, allowing bright GRB observations to strongly constrain the existence of heavy ALPs. By adding ALP interactions to existing models of GRB fireballs, we set competitive bounds on the ALP-photon coupling down to $g_{a \gamma \gamma} \sim 4 \times 10^{-12}~{\mathrm{GeV}^{-1}}$ for ALPs in the mass range of 200 MeV - 5 GeV.