Cosmic-ray origin of $\gtrsim 10$ TeV gamma-rays in GRB~221009A
Pre-published on:
July 25, 2023
Published on:
September 27, 2024
Abstract
On October 9, 2022, the Swift-BAT and Fermi-GBM telescopes detected the brightest long gamma-ray burst (GRB) observed so far. This provides us an opportunity to understand the high-energy processes in extreme transient phenomena. High-energy photons upto $\gtrsim 10$ TeV, and as high as 18 TeV were detected by the LHAASO detector. Conventional leptonic models such as synchrotron and synchrotron self-Compton are insufficient to explain the emission of such high-energy photons in the afterglow phase. In this work, we use a leptonic model for the flux of $\gamma$-rays observed by the Fermi-LAT detector in the energy range of 0.1-1 GeV. This flux is severely attenuated due to $\gamma\gamma$ pair production interaction with the extragalactic background photons. We invoke an alternate process for the explanation of the high-energy photons originating in ultrahigh-energy cosmic rays. These cosmic rays, accelerated in the GRB blastwave can escape the source and initiate an electromagnetic cascade in the extragalactic medium. The resulting $\gamma$-ray flux along our line of sight can explain the observation of $\gtrsim10$ TeV photons, detected by LHAASO, requiring a fraction of the GRB blastwave energy in ultrahigh-energy cosmic rays. This can be the first indirect signature of ultrahigh-energy cosmic-ray acceleration in GRBs.
DOI: https://doi.org/10.22323/1.444.0668
How to cite
Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating
very compact bibliographies which can be beneficial to authors and
readers, and in "proceeding" format
which is more detailed and complete.