Heavy axions can disrupt <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -ray bursts

Axionlike particles (ALPs) can be produced in the hot dense plasma of fireballs that develop in the initial stage of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>γ</a:mi> </a:math> -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 rethermalize 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 <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>g</c:mi> <c:mrow> <c:mi>a</c:mi> <c:mi>γ</c:mi> <c:mi>γ</c:mi> </c:mrow> </c:msub> <c:mo>∼</c:mo> <c:mn>4</c:mn> <c:mo>×</c:mo> <c:msup> <c:mn>10</c:mn> <c:mrow> <c:mo>−</c:mo> <c:mn>12</c:mn> </c:mrow> </c:msup> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:msup> <c:mrow> <c:mi>GeV</c:mi> </c:mrow> <c:mrow> <c:mo>−</c:mo> <c:mn>1</c:mn> </c:mrow> </c:msup> </c:math> for ALPs in the mass range of 200 MeV–5 GeV.