Gamma-Ray Bursts in the Last Observing Window: the >10 GeV Energy Band

Thanks to many space-borne detectors such as the Swift and Fermi satellites and numerous ground-based followed-up telescopes, gamma-ray bursts (GRBs) are now quickly covered in virtually every wavelength in the electromagnetic spectrum. One of the main scientific objectives of the Fermi’s two instruments: Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) are the study of GRBs. Covering the energy range above 30 MeV, the LAT has seen more than a hundred GRBs and have seen tens of photons above 10 GeV from several bright GRBs, limited only by its collective area. In addition, the H.E.S.S. experiment has now entered its second phase by adding a fifth telescope of 600 square-metre mirror area to the centre of the array. This new telescope has widened the energy range of the array, allowing it to probe the sub-100 GeV range while maintaining the large collection area of ground based gamma-ray observatories, essential to probing short-term variability at these energies. In this talk, I will review recent GRB observations at >10 GeV and discuss the corresponding radiation mechanisms in the afterglow.