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 (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.
Cite
@article{arxiv.2409.04580,
title = {GRB 221009A: the B.O.A.T Burst that Shines in Gamma Rays},
author = {M. Axelsson and M. Ajello and M. Arimoto and L. Baldini and J. Ballet and M. G. Baring and C. Bartolini and D. Bastieri and J. Becerra Gonzalez and R. Bellazzini and B. Berenji and E. Bissaldi and R. D. Blandford and R. Bonino and P. Bruel and S. Buson and R. A. Cameron and R. Caputo and P. A. Caraveo and E. Cavazzuti and C. C. Cheung and G. Chiaro and N. Cibrario and S. Ciprini and G. Cozzolongo and P. Cristarella Orestano and M. Crnogorcevic and A. Cuoco and S. Cutini and F. D'Ammando and S. De Gaetano and N. Di Lalla and A. Dinesh and R. Di Tria and L. Di Venere and A. Domínguez and S. J. Fegan and E. C. Ferrara 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 N. Giglietto and M. Giliberti and R. Gill and F. Giordano and M. Giroletti and J. Granot and D. Green and I. A. Grenier and S. Guiriec and M. Gustafsson and M. Hashizume and E. Hays and J. W. Hewitt and D. Horan and T. Kayanoki and M. Kuss and A. Laviron and J. Li and I. Liodakis and F. Longo and F. Loparco and L. Lorusso and B. Lott and M. N. Lovellette and P. Lubrano and S. Maldera and D. Malyshev and A. Manfreda and G. Martí-Devesa and R. Martinelli and I. Martinez Castellanos and M. N. Mazziotta and J. E. McEnery and I. Mereu and M. Meyer and P. F. Michelson and N. Mirabal and W. Mitthumsiri and T. Mizuno and P. Monti-Guarnieri and M. E. Monzani and T. Morishita and A. Morselli and I. V. Moskalenko and M. Negro and R. Niwa and N. Omodei and M. Orienti and E. Orlando and D. Paneque and G. Panzarini and M. Persic and M. Pesce-Rollins and V. Petrosian and R. Pillera and F. Piron and T. A. Porter and G. Principe and J. L. Racusin and S. Rainò and R. Rando and B. Rani and M. Razzano and S. Razzaque and A. Reimer and O. Reimer and F. Ryde and M. Sánchez-Conde and P. M. Saz Parkinson and D. Serini and C. Sgrò and V. Sharma and E. J. Siskind and G. Spandre and P. Spinelli and D. J. Suson and H. Tajima and D. Tak and J. B. Thayer and D. F. Torres and J. Valverde and G. Zaharijas and S. Lesage and M. S. Briggs and E. Burns and S. Bala and P. N. Bhat and W. H. Cleveland and S. Dalessi and C. de Barra and M. Gibby and M. M. Giles and R. Hamburg and B. A. Hristov and C. M. Hui and D. Kocevski and B. Mailyan and C. Malacaria and S. McBreen and S. Poolakkil and O. J. Roberts and L. Scotton and P. Veres and A. von Kienlin and C. A. Wilson-Hodge and J. Wood},
journal= {arXiv preprint arXiv:2409.04580},
year = {2024}
}
Comments
60 pages, 38 figures, 9 tables