AGILE gamma-ray detection of the exceptional GRB 221009A
Abstract
Gamma-ray emission in the MeV-GeV range from explosive cosmic events is of invaluable relevance to understanding physical processes related to the formation of neutron stars and black holes. Here we report on the detection by the AGILE satellite in the MeV-GeV energy range of the remarkable long-duration gamma-ray burst GRB 221009A. The AGILE onboard detectors have good exposure to GRB 221009A during its initial crucial phases. Hard X-ray/MeV emission in the prompt phase lasted hundreds of seconds, with the brightest radiation being emitted between 200 and 300 seconds after the initial trigger. Very intense GeV gamma-ray emission is detected by AGILE in the prompt and early afterglow phase up to 10,000 seconds. Time-resolved spectral analysis shows time-variable MeV-peaked emission simultaneous with intense power-law GeV radiation that persists in the afterglow phase. The coexistence during the prompt phase of very intense MeV emission together with highly nonthermal and hardening GeV radiation is a remarkable feature of GRB 221009A. During the prompt phase, the event shows spectrally different MeV and GeV emissions that are most likely generated by physical mechanisms occurring in different locations. AGILE observations provide crucial flux and spectral gamma-ray information regarding the early phases of GRB 221009A during which emission in the TeV range was reported.
Keywords
Cite
@article{arxiv.2309.10515,
title = {AGILE gamma-ray detection of the exceptional GRB 221009A},
author = {M. Tavani and G. Piano and A. Bulgarelli and L. Foffano and A. Ursi and F. Verrecchia and C. Pittori and C. Casentini and A. Giuliani and F. Longo and G. Panebianco and A. Di Piano and L. Baroncelli and V. Fioretti and N. Parmiggiani and A. Argan and A. Trois and S. Vercellone and M. Cardillo and L. A. Antonelli and G. Barbiellini and P. Caraveo and P. W. Cattaneo and A. W. Chen and E. Costa and E. Del Monte and G. Di Cocco and I. Donnarumma and Y. Evangelista and M. Feroci and F. Gianotti and C. Labanti and F. Lazzarotto and P. Lipari and F. Lucarelli and M. Marisaldi and S. Mereghetti and A. Morselli and L. Pacciani and A. Pellizzoni and F. Perotti and P. Picozza and M. Pilia and M. Rapisarda and A. Rappoldi and A. Rubini and P. Soffitta and M. Trifoglio and V. Vittorini and F. D'Amico},
journal= {arXiv preprint arXiv:2309.10515},
year = {2024}
}
Comments
Accepted for publication in ApJL on September 19, 2023. Published online on October 17, 2023. Revised Figure 5 (June 13, 2024)