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

Fermi LAT Collaboration; Fermi GBM collaboration

doi:10.3847/1538-4365/ada272

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

Fermi LAT Collaboration
, Fermi GBM collaboration

Physics Department
KTH Royal Institute of Technology
Oskar Klein Centre
Department of Physics and Astronomy
Clemson University
Faculty of Mathematics and Physics
Kanazawa University
University of Pisa
CEA/UVSQ/CNRS
Department of Physics and Astronomy
Rice University
INFN Sezione di Bari
Università di Trento
INFN
University of Padova
Instituto de Astrofísica de Canarias
Research Unit; CIBERNED and Universidad de La Laguna
Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
Department of Physics and Astronomy
California State University-Los Angeles
Politecnico di Bari
Kavli Institute for Particle Astrophysics and Cosmology
INFN Sezione di Torino
Dipartimento di Fisica
University of Turin
Institut für Theoretische Physik und Astrophysik
University of Würzburg
Astrophysics Science Division
NASA Goddard Space Flight Center
INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan
Science and Research Directorate
Space Science Division
Naval Research Laboratory
INFN Roma Tor Vergata
Friedrich-Alexander University (FAU) Erlangen-Nürnberg and Universitätsklinikum Erlangen
University of Perugia
INFN Sezione di Perugia
University of Maryland
INAF Istituto di Radioastronomia
Grupo de Altas Energías
Complutense University
Center for Research and Exploration in Space Science and Technology
Faculty of Physics and Astronomy
Ruhr-University Bochum
Department of Physical Science
Hiroshima University
University of Rome “Tor Vergata”

Research output: Contribution to journal › Article › peer-review

23 Citations (Scopus)

Abstract

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.

Original language	English
Article number	24
Journal	Astrophysical Journal, Supplement Series
Volume	277
Issue number	1
DOIs	https://doi.org/10.3847/1538-4365/ada272
Publication status	Published - 1 Mar 2025

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10.3847/1538-4365/ada272

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@article{012b20371db740bea9bce56098552139,

title = "GRB 221009A: The B.O.A.T. Burst that Shines in Gamma Rays",

abstract = "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.",

author = "\{Fermi LAT Collaboration\} and \{Fermi GBM collaboration\} and M. Axelsson and M. Ajello and M. Arimoto and L. Baldini and J. Ballet and Baring, \{M. G.\} and C. Bartolini and D. Bastieri and \{Becerra Gonzalez\}, J. and R. Bellazzini and B. Berenji and E. Bissaldi and Blandford, \{R. D.\} and R. Bonino and P. Bruel and S. Buson and Cameron, \{R. A.\} and R. Caputo and Caraveo, \{P. A.\} and E. Cavazzuti and Cheung, \{C. C.\} and G. Chiaro and N. Cibrario and S. Ciprini and G. Cozzolongo and \{Cristarella Orestano\}, P. and M. Crnogorcevic and A. Cuoco and S. Cutini and F. D{\textquoteright}Ammando and \{De Gaetano\}, S. and \{Di Lalla\}, N. and A. Dinesh and \{Di Tria\}, R. and \{Di Venere\}, L. and A. Dom{\'i}nguez and Fegan, \{S. J.\} and Ferrara, \{E. C.\} and A. Fiori and A. Franckowiak and Y. Fukazawa and S. Funk and P. Fusco and G. Galanti and F. Gargano and C. Gasbarra and S. Germani and F. Giacchino and D. Horan and A. Laviron",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s).",

year = "2025",

month = mar,

day = "1",

doi = "10.3847/1538-4365/ada272",

language = "English",

volume = "277",

journal = "Astrophysical Journal, Supplement Series",

issn = "0067-0049",

publisher = "American Astronomical Society",

number = "1",

}

TY - JOUR

T1 - GRB 221009A

T2 - The B.O.A.T. Burst that Shines in Gamma Rays

AU - Fermi LAT Collaboration

AU - Fermi GBM collaboration

AU - Axelsson, M.

AU - Ajello, M.

AU - Arimoto, M.

AU - Baldini, L.

AU - Ballet, J.

AU - Baring, M. G.

AU - Bartolini, C.

AU - Bastieri, D.

AU - Becerra Gonzalez, J.

AU - Bellazzini, R.

AU - Berenji, B.

AU - Bissaldi, E.

AU - Blandford, R. D.

AU - Bonino, R.

AU - Bruel, P.

AU - Buson, S.

AU - Cameron, R. A.

AU - Caputo, R.

AU - Caraveo, P. A.

AU - Cavazzuti, E.

AU - Cheung, C. C.

AU - Chiaro, G.

AU - Cibrario, N.

AU - Ciprini, S.

AU - Cozzolongo, G.

AU - Cristarella Orestano, P.

AU - Crnogorcevic, M.

AU - Cuoco, A.

AU - Cutini, S.

AU - D’Ammando, F.

AU - De Gaetano, S.

AU - Di Lalla, N.

AU - Dinesh, A.

AU - Di Tria, R.

AU - Di Venere, L.

AU - Domínguez, A.

AU - Fegan, S. J.

AU - Ferrara, E. C.

AU - Fiori, A.

AU - Franckowiak, A.

AU - Fukazawa, Y.

AU - Funk, S.

AU - Fusco, P.

AU - Galanti, G.

AU - Gargano, F.

AU - Gasbarra, C.

AU - Germani, S.

AU - Giacchino, F.

AU - Horan, D.

AU - Laviron, A.

PY - 2025/3/1

Y1 - 2025/3/1

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/105000176708

U2 - 10.3847/1538-4365/ada272

DO - 10.3847/1538-4365/ada272

M3 - Article

AN - SCOPUS:105000176708

SN - 0067-0049

VL - 277

JO - Astrophysical Journal, Supplement Series

JF - Astrophysical Journal, Supplement Series

IS - 1

M1 - 24

ER -

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

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