Speaker
Description
The fireball model has been widely used to explain the spectral energy distribution and light curves of gamma-ray bursts (GRBs) during the afterglow phase. According to this model, particles are accelerated in external shocks, resulting in photon emission via synchrotron radiation and synchrotron self-Compton (SSC) processes. However, this framework does not fully account for all observed cases. Notably, the GeV excess detected in GRB 211211A has been attributed to external inverse-Compton (EIC) interactions, where optical kilonova photons are upscattered by electrons accelerated in the forward shock of a weaker secondary jet. Observations with the High Altitude Water Cherenkov (HAWC) gamma-ray observatory reveled photons spatially coincident with a few GRBs, detected at timescales consistent with the expected kilonova emission peak. In this work, we argue that the detected VHE photons indeed originate from these GRBs, the SSC mechanism in both forward and reverse shocks fails to account for them. Instead, we propose that these photons result from inverse-Compton scattering of kilonova photons by electrons within the reverse shock.
| Collaboration(s) | High Altitude Water Cherenkov (HAWC) Collaboration |
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