GRB 221009A: the B.O.A.T Burst that Shines in Gamma Rays
Creators: name: Axelsson, M.
name: Ajello, M.
name: Arimoto, M.
name: Baldini, L.
name: Ballet, J.
name: Baring, M. G.
name: Bartolini, C.
name: Bastieri, D.
name: Gonzalez, J. Becerra
name: Bellazzini, R.
name: Berenji, B.
name: Bissaldi, E.
name: Blandford, R. D.
name: Bonino, R.
name: Bruel, P.
name: Buson, S.
name: Cameron, R. A.
name: Caputo, R.
name: Caraveo, P. A.
name: Cavazzuti, E.
name: Cheung, C. C.
name: Chiaro, G.
name: Cibrario, N.
name: Ciprini, S.
name: Cozzolongo, G.
name: Orestano, P. Cristarella
name: Crnogorcevic, M.
name: Cuoco, A.
name: Cutini, S.
name: D'Ammando, F.
name: De Gaetano, S.
name: Di Lalla, N.
name: Dinesh, A.
name: Di Tria, R.
name: Di Venere, L.
name: Domínguez, A.
name: Fegan, S. J.
name: Ferrara, E. C.
name: Fiori, A.
name: Franckowiak, A.
name: Fukazawa, Y.
name: Funk, S.
name: Fusco, P.
name: Galanti, G.
name: Gargano, F.
name: Gasbarra, C.
name: Germani, S.
name: Giacchino, F.
name: Giglietto, N.
name: Giliberti, M.
name: Gill, R.
name: Giordano, F.
name: Giroletti, M.
name: Granot, J.
name: Green, D.
name: Grenier, I. A.
name: Guiriec, S.
name: Gustafsson, M.
name: Hashizume, M.
name: Hays, E.
name: Hewitt, J. W.
name: Horan, D.
name: Kayanoki, T.
name: Kuss, M.
name: Laviron, A.
name: Li, J.
name: Liodakis, I.
name: Longo, F.
name: Loparco, F.
name: Lorusso, L.
name: Lott, B.
name: Lovellette, M. N.
name: Lubrano, P.
name: Maldera, S.
name: Malyshev, D.
name: Manfreda, A.
name: Martí-Devesa, G.
name: Martinelli, R.
name: Castellanos, I. Martinez
name: Mazziotta, M. N.
name: McEnery, J. E.
name: Mereu, I.
name: Meyer, M.
name: Michelson, P. F.
name: Mirabal, Nestor
name: Mitthumsiri, W.
name: Mizuno, T.
name: Monti-Guarnieri, P.
name: Monzani, M. E.
name: Morishita, T.
name: Morselli, A.
name: Moskalenko, I. V.
name: Negro, M.
name: Niwa, R.
name: Omodei, N.
name: Orienti, M.
name: Orlando, E.
name: Paneque, D.
name: Panzarini, G.
name: Persic, M.
name: Pesce-Rollins, M.
name: Petrosian, V.
name: Pillera, R.
name: Piron, F.
name: Porter, T. A.
name: Principe, G.
name: Racusin, J. L.
name: Rainò, S.
name: Rando, R.
name: Rani, Bindu
name: Razzano, M.
name: Razzaque, S.
name: Reimer, A.
name: Reimer, O.
name: Ryde, F.
name: Sánchez-Conde, M.
name: Parkinson, P. M. Saz
name: Serini, D.
name: Sgrò, C.
name: Sharma, Vidushi
name: Siskind, E. J.
name: Spandre, G.
name: Spinelli, P.
name: Suson, D. J.
name: Tajima, H.
name: Tak, D.
name: Thayer, J. B.
name: Torres, D. F.
name: , Janeth
name: Zaharijas, G.
name: Lesage, S.
name: Briggs, M. S.
name: Burns, E.
name: Bala, S.
name: Bhat, P. N.
name: Cleveland, W. H.
name: Dalessi, S.
name: De Barra, C.
name: Gibby, M.
name: Giles, M. M.
name: Hamburg, R.
name: Hristov, B. A.
name: Hui, C. M.
name: Kocevski, D.
name: Mailyan, B.
name: Malacaria, C.
name: McBreen, S.
name: Poolakkil, S.
name: Roberts, O. J.
name: Scotton, L.
name: Veres, P.
name: Von Kienlin, A.
name: Wilson-Hodge, C. A.
name: Wood, J.
Publisher: name: Maryland Shared Open Access Repository
Year: 2024
Subjects: Astrophysics - High Energy Astrophysical Phenomena

description: We present a complete analysis of Fermi Large Area Telescope (LAT) data of GRB 221009A, the brightest Gamma-Ray Burst (GRB) ever detected. The burst emission above 30 MeV detected by the LAT preceded by 1 s the low-energy (&lt; 10 MeV) pulse that triggered the Fermi Gamma-Ray Burst Monitor (GBM), as has been observed in other GRBs. The prompt phase of GRB 221009A lasted a few hundred seconds. It was so bright that we identify a Bad Time Interval (BTI) of 64 seconds caused by the extremely high flux of hard X-rays and soft gamma rays, during which the event reconstruction efficiency was poor and the dead time fraction quite high. The late-time emission decayed as a power law, but the extrapolation of the late-time emission during the first 450 seconds suggests that the afterglow started during the prompt emission. We also found that high-energy events observed by the LAT are incompatible with synchrotron origin, and, during the prompt emission, are more likely related to an extra component identified as synchrotron self-Compton (SSC). A remarkable 400 GeV photon, detected by the LAT 33 ks after the GBM trigger and directionally consistent with the location of GRB 221009A, is hard to explain as a product of SSC or TeV electromagnetic cascades, and the process responsible for its origin is uncertain. Because of its proximity and energetic nature, GRB 221009A is an extremely rare event.