TY - JOUR
T1 - H.E.S.S. Follow-up Observations of GRB 221009A
AU - H.E.S.S. Collaboration
AU - Aharonian, F.
AU - Benkhali, F. Ait
AU - Aschersleben, J.
AU - Ashkar, H.
AU - Backes, M.
AU - Baktash, A.
AU - Martins, V. Barbosa
AU - Batzofin, R.
AU - Becherini, Y.
AU - Berge, D.
AU - Bernlöhr, K.
AU - Bi, B.
AU - Böttcher, M.
AU - Boisson, C.
AU - Bolmont, J.
AU - de Bony de Lavergne, M.
AU - Borowska, J.
AU - Bouyahiaoui, M.
AU - Bradascio, F.
AU - Breuhaus, M.
AU - Brose, R.
AU - Brun, F.
AU - Bruno, B.
AU - Bulik, T.
AU - Burger-Scheidlin, C.
AU - Caroff, S.
AU - Casanova, S.
AU - Celic, J.
AU - Cerruti, M.
AU - Chand, T.
AU - Chandra, S.
AU - Chen, A.
AU - Chibueze, J.
AU - Chibueze, O.
AU - Cotter, G.
AU - Dai, S.
AU - Mbarubucyeye, J. Damascene
AU - Devin, J.
AU - Djannati-Ataï, A.
AU - Dmytriiev, A.
AU - Doroshenko, V.
AU - Egberts, K.
AU - Einecke, S.
AU - Ernenwein, J. P.
AU - Fegan, S.
AU - de Clairfontaine, G. Fichet
AU - Filipovic, M.
AU - Fontaine, G.
AU - Füßling, M.
AU - Funk, S.
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - GRB 221009A is the brightest gamma-ray burst (GRB) ever detected. To probe the very-high-energy (VHE; >100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hr 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 Φ UL 95 % = 9.7 × 10 − 12 erg cm − 2 s − 1 above E 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 spectral energy distribution occurring above the X-ray band. Compared to the VHE-bright GRB 190829A, the upper limits for GRB 221009A 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 GRB 221009A, effectively ruling out an IC-dominated scenario.
AB - GRB 221009A is the brightest gamma-ray burst (GRB) ever detected. To probe the very-high-energy (VHE; >100 GeV) emission, the High Energy Stereoscopic System (H.E.S.S.) began observations 53 hr 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 Φ UL 95 % = 9.7 × 10 − 12 erg cm − 2 s − 1 above E 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 spectral energy distribution occurring above the X-ray band. Compared to the VHE-bright GRB 190829A, the upper limits for GRB 221009A 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 GRB 221009A, effectively ruling out an IC-dominated scenario.
UR - https://www.scopus.com/pages/publications/85151509935
U2 - 10.3847/2041-8213/acc405
DO - 10.3847/2041-8213/acc405
M3 - Article
AN - SCOPUS:85151509935
SN - 2041-8205
VL - 946
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L27
ER -