http://arxiv.org/abs/2210.13349
The brightest long gamma-ray burst detected so far by the Swift-BAT and Fermi-GBM telescopes, GRB~221009A provides an unprecedented opportunity for understanding the high-energy processes in extreme transient phenomena. We find that the conventional leptonic models, synchrotron and synchrotron-self-Compton, for the afterglow emission from this source is unable to explain observation of $\gamma$ rays, by the LHAASO detector, extending up to 18 TeV energies. We model $\gamma$-ray spectrum estimated in the energy range 0.1-1 GeV, by the Fermi-LAT detector. The flux predicted by our leptonic models is severely attenuated at $> 1$ TeV due to $\gamma\gamma$ pair production with extragalactic background light, and hence an additional component is required. Ultrahigh-energy cosmic rays can be accelerated in the GRB jet and their propagation induces an electromagnetic cascade in the extragalactic medium. The line of sight component of this flux can explain TeV emission detected by LHAASO, requiring a fraction of the GRB blastwave energy in ultrahigh-energy cosmic rays. This could be the first direct evidence of ultrahigh-energy cosmic-ray acceleration in GRBs.
S. Das and S. Razzaque
Tue, 25 Oct 22
68/111
Comments: 5 pages, 2 figures, comments are welcome