H.E.S.S. follow-up observations of GRB221009A

Abstract

GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, $>$\!100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hours after the triggering event, when the brightness of the moonlight no longer precluded observations. We derive differential and integral upper limits using H.E.S.S. data from the third, fourth, and ninth nights after the initial GRB detection, after applying atmospheric corrections. The combined observations yield an integral energy flux upper limit of ${\Phi }_{\mathrm{UL}}^{95\%}=9.7\times 10^{-12}\mathrm{erg}\mathrm{c}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$ above $E_{\mathrm{thr}}=650$ GeV. The constraints derived from the H.E.S.S. observations complement the available multiwavelength data. The radio to X-ray data are consistent with synchrotron emission from a single electron population, with the peak in the SED occurring above the X-ray band. Compared to the VHE-bright GRB190829A, the upper limits for GRB221009A imply a smaller gamma-ray to X-ray flux ratio in the afterglow. Even in the absence of a detection, the H.E.S.S. upper limits thus contribute to the multiwavelength picture of GRB221009A, effectively ruling out an IC dominated scenario.

10 pages, 4 figures. Accepted for publication in APJL. Corresponding authors: J. Damascene Mbarubucyeye, H. Ashkar, S. J. Zhu, B. Reville, F. Schüssler

References in corpus (14)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• 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
• A very-high-energy component deep in the Gamma-ray Burst afterglow
• Klein-Nishina Effects on Optically Thin Synchrotron and Synchrotron Self-Compton Spectrum
• Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow
• Gamma-Hadron Separation in Very-High-Energy gamma-ray astronomy using a multivariate analysis method
• Multi-wavelength view of the close-by GRB 190829A sheds light on gamma-ray burst physics
• Ultra-high energy Inverse Compton emission from Galactic electron accelerators
• A Run-Wise Simulation and Analysis Framework for Imaging Atmospheric Cherenkov Telescope Arrays
• The implications of TeV detected GRB afterglows for acceleration at relativistic shocks
• The variable absorption in the X-ray spectrum of GRB 190114C

Cited by in corpus (10)

• A Narrow Uniform Core with a Wide Structured Wing: Modeling the TeV and Multi-wavelength Afterglows of GRB 221009A
• The origin of very-high-energy gamma-rays from GRB 221009A: implications for reverse shock proton synchrotron emission
• Impact of Cosmology on Lorentz Invariance Violation Constraints from GRB Time-Delays
• GRB 221009A: Spectral signatures based on ALPs candidates
• Impact of Satellite Trails on H.E.S.S. Astronomical Observations
• Probing for Lorentz Invariance Violation in Pantheon Plus Dominated Cosmology
• GRB 221009A: Observations with LST-1 of CTAO and Implications for Structured Jets in Long Gamma-Ray Bursts
• Two-component jet model for the afterglow emission of GRB 201216C and GRB 221009A and implications for jet structure of very-high-energy gamma-ray bursts
• A photohadronic interpretation of the H.E.S.S. afterglow observations from GRB 221009A
• Extreme Transients in Gamma Rays