Synchrotron self-Compton emission from external shocks as the origin of the sub-TeV emission in GRB 180720B and GRB 190114C

Understand

Recently, very high-energy photons above 100 GeV were reported to be detected from GRB~190114C and GRB~180720B at, respectively, 100-1000 s and 10 hours after the burst.

• We model the available broad-band data of both GRBs with the synchrotron plus synchrotron self-Compton (SSC) emission of the afterglow shocks.
• We find that the sub-TeV emission of GRB~180720B can be interpreted as the SSC emission from afterglow shocks expanding in a constant density circum-burst medium.
• The SSC emission of GRB~190114C dominates over the synchrotron component from GeV energies at $\sim100$ s, which can explain the possible hard spectrum of the GeV emission at this time.