astrolunch: Sylvia Zhu (DESY)

Tue, 22/06/202112:30-13:30

Title: Exploring the Late-Time Gamma-Ray Burst Afterglow at Very High Energies with H.E.S.S.

Abstract: Gamma-ray bursts (GRBs) are some of the most energetic explosions since the Big Bang. As GRBs are transient objects, the study of GRBs is often advanced by detections of spectacular individual events. Recently, H.E.S.S. detected Very High Energy (VHE, >100 GeV) emission from GRB 190829A for three consecutive nights, up to 56 hours after the burst began, providing an unprecedented opportunity to study the late-time VHE afterglow spectrum. By combining the simultaneous Swift-XRT and H.E.S.S. observations, some curious similarities of the temporal and spectral behavior of the X-ray and VHE emission can be seen. I will give a brief overview of the recent detections of GRBs by VHE facilities like H.E.S.S. and MAGIC, and discuss the questions that GRB 190829A raises, that challenge the standard models for VHE afterglow modelling and GRB physics.