GRB 221009A: A light dark matter burst or an extremely bright Inverse Compton component?

Abstract

Gamma-Ray Bursts (GRBs) are considered potential Very High-Energy (VHE) photon emitters because the large amount of energy released and the strong magnetic fields involved in their jets. However, VHE photons are not expected from bursts beyond a redshift of z ≳ 0.1 because of the attenuation of photons with the Extragalactic Background Light (EBL). The recent observation of photons with energies of 18 and 251 TeV from GRB 221009A (z=0.151) last October 9th, 2022, could be challenging what we know about the TeV-emission mechanisms and the EBL. Recent works exploring candidates of dark matter, cosmic rays, and other alternatives appeared. In this work, we explore possible scenarios regarding Axion-Like Particles (ALPs) and dark photon mechanisms and discuss the implications in GRB energetics. We find that the ALPs and dark photon scenarios can explain the 18 TeV photon but not the 251 TeV photon.