The second H.E.S.S. gamma-ray burst catalogue: 15 years of observations with the H.E.S.S. telescopes

Abstract

Recent observational efforts using imaging atmospheric Cherenkov telescopes (IACTs) have led to firm detections of very-high-energy (VHE) signals from bright gamma-ray bursts (GRBs), often at moderate redshifts. This work presents 15 years of H.E.S.S. GRB observations and examines their implications through population comparisons and selected modelling cases. GRBs are a key science target of the High Energy Stereoscopic System (H.E.S.S.). With a low-energy threshold ($\lesssim$100 GeV) and rapid repointing capabilities, H.E.S.S. can begin follow-up observations within tens of seconds after a GRB trigger, covering the late prompt or early afterglow phases. We report GRB follow-up observations with H.E.S.S. from 2004 to 2019, which resulted in no significant VHE signals (aside from the detections of GRB~180720B and GRB~190829A). The resulting upper limits comprise the largest set available for GRBs at VHE. A subset of bursts with favourable conditions were selected for X-ray analysis and emission modelling. Population studies were performed to compare detected and non-detected GRBs. The results indicate that VHE-detected GRBs are not a distinct population, but tend to feature luminous X-ray emission and favourable redshift and observing conditions. This highlights the potential of next-generation IACTs such as the Cherenkov Telescope Array Observatory (CTAO), whose lower energy threshold will enhance the detection of fainter and more distant GRBs.

Published in Astronomy and Astrophysics

References in corpus (20)

• An online repository of Swift/XRT light curves of GRBs
• Observations of the Crab Nebula with H.E.S.S
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• Teraelectronvolt emission from the $\gamma$-ray burst GRB 190114C
• GRB Radiative Efficiencies Derived from the Swift Data: GRBs vs. XRFs, Long vs. Short
• A very-high-energy component deep in the Gamma-ray Burst afterglow
• Search for TeV Gamma-ray Emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S
• Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow
• Very high energy gamma-ray emission beyond 10 TeV from GRB 221009A
• Prompt Emission of High Energy Photons from Gamma Ray Bursts
• GRB 071003: Broadband Follow-up Observations of a Very Bright Gamma-Ray Burst in a Galactic Halo
• A real-time transient detector and the Living Swift-XRT Point Source catalogue
• H.E.S.S. observations of gamma-ray bursts in 2003-2007
• Observations of the Crab Nebula and Pulsar with the Large-Sized Telescope Prototype of the Cherenkov Telescope Array
• MAGIC detection of GRB 201216C at $z=1.1$
• The implications of TeV detected GRB afterglows for acceleration at relativistic shocks
• Probing the EBL evolution at high redshift using GRBs detected with the Fermi-LAT
• Revisiting Tests of Lorentz Invariance with Gamma-ray Bursts: Effects of Intrinsic Lags
• The H.E.S.S. transients follow-up system
• The formation of hard VHE spectra from GRB afterglow via Two-Zone Synchrotron Self-Compton Emission