GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays

Journal Article · Fri Feb 28 00:00:00 EST 2025 · The Astrophysical Journal. Supplement Series

DOI:https://doi.org/10.3847/1538-4365/ada272· OSTI ID:2573722

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

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 (<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 of 64 s 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 s 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.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Contributing Organization: Fermi GBM collaboration; Fermi LAT collaboration
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 2573722
• Journal Information: The Astrophysical Journal. Supplement Series, Journal Name: The Astrophysical Journal. Supplement Series Journal Issue: 1 Vol. 277; ISSN 1538-4365; ISSN 0067-0049
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

gamma-ray astronomy
gamma-ray bursts
high energy astrophysics