The brightest gamma ray burst (GRB) ever observed, GRB221009A, produced a surprisingly large flux of gamma rays with multi-TeV energies, which are expected to be absorbed in interactions with extragalactic background light (EBL). If the highest energy gamma rays were produced at the source, their spectral shape would have to exhibit a nonphysical spike even for the lowest levels of EBL. We show that, for widely accepted models of EBL, the data can be explained by secondary gamma rays produced in cosmic ray interactions along the line of sight, as long as the extragalactic magnetic fields along the line of sight are 10−16G or smaller, assuming 1 Mpc correlation length. Our interpretation supports the widely held expectation that GRB jets can accelerate cosmic rays to energies as high as 10 EeV and above, and it has implications for understanding the magnitudes of EGMFs.
@article{arxiv.2405.05402,
title = {The possibility of multi-TeV secondary gamma rays from GRB221009A},
author = {Oleg Kalashev and Felix Aharonian and Warren Essey and Yoshiyuki Inoue and Alexander Kusenko},
journal= {arXiv preprint arXiv:2405.05402},
year = {2025}
}
Comments
7 pages, 3 figures, accepted for publication in Phys. Rev. D