http://arxiv.org/abs/2210.15857
Gamma-ray bursts (GRBs) have been considered as potential very high-energy photon emitters due to the large amount of energy released as well as the strong magnetic fields involved. However, the detection of TeV photons is not expected from bursts beyond a redshift of $z\gtrsim 0.1$ due to the attenuation caused by the interaction with photons from the extragalactic background light (EBL). The observation of an 18-TeV photon from GRB 221009A (z=0.15) last October 9th, 2022 has challenged what we know about the TeV-emission mechanisms and the extragalactic background. Recent explanations exploiting candidates of dark matter have started to appear. In this paper, we discuss the required conditions and limitations within the most plausible scenario, synchrotron-self Compton (SSC) radiation in the GRB afterglow, to interpret the one 18-TeV photon observation besides the EBL. To avoid the Klein-Nishina effect, we find an improbable value of the microphysical magnetic parameter below $10^{-6}$ for a circumburst medium $>{\rm cm^{-3}}$ (expected in the collapsar scenario). Therefore, we explore possible scenarios in terms of ALPs and dark photon mechanisms to interpret this highly-energetic photon and discuss the implications in the GRB energetics. We find the ALPs and dark photon scenarios explain the 18 TeV photon but not the 251 TeV photon.
M. González, D. Rojas, A. Pratts, et. al.
Mon, 31 Oct 22
14/60
Comments: 15 pages, 5 figures, 5 tables