H.E.S.S. follow-up observations of GRB221009A
Creators: name: Aharonian, F.
name: Benkhali, F. Ait
name: Aschersleben, J.
name: Ashkar, H.
name: Backes, M.
name: Baktash, A.
name: Barbosa Martins, V.
name: Batzofin, R.
name: Becherini, Y.
name: Berge, D.
name: Bernlohr, K.
name: Bi, B.
name: Bottcher, M.
name: Boisson, C.
name: Bolmont, J.
name: de Bony de Lavergne, M.
name: Borowska, J.
name: Bouyahiaoui, M.
name: Bradascio, F.
name: Breuhaus, M.
name: Brose, R.
name: Brun, F.
name: Bruno, B.
name: Bulik, T.
name: Burger-Scheidlin, C.
name: Caroff, S.
name: Casanova, S.
name: Celic, J.
name: Cerruti, M.
name: Chand, T.
name: Chandra, S.
name: Chen, A.
name: Chibueze, J.
name: Chibueze, O.
name: Cotter, G.
name: Dai, S.
name: Mbarubucyeye, Jean Damascene
name: Devin, J.
name: Djannati-Atai, A.
name: Dmytriiev, A.
name: Doroshenko, V.
name: Egberts, K.
name: Einecke, S.
name: Ernenwein, J.-P.
name: Fegan, S.
name: Fichet de Clairfontaine, G.
name: Filipovic, M.
name: Fontaine, G.
name: Fußling, M.
name: Funk, S.
name: Gabici, S.
name: Ghafourizadeh, S.
name: Giavitto, G.
name: Glawion, D.
name: Glicenstein, J. F.
name: Goswami, P.
name: Grolleron, G.
name: Grondin, M.-H.
name: Hinton, J. A.
name: Holch, T. L.
name: Holler, M.
name: Horns, D.
name: Huang, Zhiqiu
name: Jamrozy, M.
name: Jankowsky, F.
name: Joshi, V.
name: Jung-Richardt, I.
name: Kasai, E.
name: Katarzynski, K.
name: Khatoon, R.
name: Khelifi, B.
name: Klúzniak, W.
name: Komin, Nu.
name: Konno, R.
name: Kosack, K.
name: Kostunin, D.
name: Lang, R. G.
name: Le Stum, S.
name: Leitl, F.
name: Lemiere, A.
name: Lemoine-Goumard, M.
name: Lenain, J.-P.
name: Leuschner, F.
name: Lohse, T.
name: Lypova, I.
name: Mackey, J.
name: Malyshev, D.
name: Malyshev, D.
name: Marandon, V.
name: Marchegiani, P.
name: Marcowith, A.
name: Martí-Devesa, G.
name: Marx, R.
name: Meyer, M.
name: Mitchell, A.
name: Mohrmann, L.
name: Montanari, A.
name: Moulin, E.
name: Murach, T.
name: Nakashima, K.
name: de Naurois, M.
name: Niemiec, J.
name: Noel, A. Priyana
name: O'Brien, P.
name: Ohm, S.
name: Olivera-Nieto, L.
name: de Ona Wilhelmi, E.
name: Ostrowski, M.
name: Panny, S.
name: Panter, M.
name: Parsons, R. D.
name: Peron, G.
name: Prokhorov, D. A.
name: Prokoph, H.
name: Puhlhofer, G.
name: Punch, M.
name: Quirrenbach, A.
name: Reichherzer, P.
name: Reimer, A.
name: Reimer, O.
name: Ren, H.
name: Renaud, M.
name: Reville, B.
name: Rieger, F.
name: Rowell, G.
name: Rudak, B.
name: Ruiz-Velasco, E.
name: Sahakian, V.
name: Salzmann, H.
name: Santangelo, A.
name: Sasaki, M.
name: Schafer, J.
name: Schussler, F.
name: Schutte, H. M.
name: Schwanke, U.
name: Shapopi, J. N. S.
name: Specovius, A.
name: Spencer, S.
name: Stawarz, L.
name: Steenkamp, R.
name: Steinmassl, S.
name: Steppa, C.
name: Sushch, I.
name: Suzuki, H.
name: Takahashi, T.
name: Tanaka, T.
name: Terrier, R.
name: Tsuji, N.
name: Uchiyama, Y.
name: Vecchi, M.
name: Venter, C.
name: Vink, J.
name: Wagner, S. J.
name: White, R.
name: Wierzcholska, A.
name: Wong, Yu Wun
name: Zacharias, M.
name: Zargaryan, D.
name: Zdziarski, A. A.
name: Zech, A.
name: Zhu, Sylvia Jiechen
name: Zywucka, And N.
name: H. E. S. S. Collaboration
Publisher: name: Deutsches Elektronen-Synchrotron, DESY, Hamburg
Year: 2023
Subjects: gamma ray, burst
flux, ratio
energy, flux
energy, high
atmosphere, correction
flux, upper limit
X-ray, flux
HESS
GeV
VHE
synchrotron
5/3
brightness
electron

description: GRB221009A is the brightest gamma-ray burst ever detected. To probe the very-high-energy (VHE, $&gt;$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 $\Phi_\mathrm{UL}^{95\%} = 9.7 \times 10^{-12}~\mathrm{erg\,cm^{-2}\,s^{-1}}$ 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.