Speaker
Description
The most energetic explosions in the Universe after the Big Bang are Gamma-Ray Bursts (GRBs). They emit intense and brief flashes of gamma-rays initially during their prompt phase, followed by a long afterglow phase observed in all the wavelengths. Multi-wavelength observation of GRB afterglow provides some hints for the nature of the emission mechanism. However, the GRBs are not observed in very-high-energies (VHEs) until 2018. Currently, the High Energy Stereoscopic System (H.E.S.S.) at Namibia is the only imaging atmospheric Cherenkov telescope array in the Southern Hemisphere that observes VHE gamma-ray sources. Since the completion of its installation in 2004, H.E.S.S. has been actively searching for the GRBs in GeV-TeV energies. For the very first time, the GRBs are detected in VHE gamma-rays in recent years and H.E.S.S. has majorly contributed towards this discovery. In this talk, I will give an overview of GRB observations by H.E.S.S. and discuss its discovery of VHE gamma-rays from GRB180720B and GRB190829A.
