AGILE Gamma-Ray Detection of the Exceptional GRB 221009A

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 s 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 s. 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.

Volume

956

Issue

1

Start page

L23

Uri

http://hdl.handle.net/20.500.12386/37032

Url

https://iopscience.iop.org/article/10.3847/2041-8213/acfaff

https://api.elsevier.com/content/abstract/scopus_id/85175641632

Issn Identifier

2041-8205

Ads BibCode

2023ApJ...956L..23T

Rights

open.access

File(s)

Name

Tavani_2023_ApJL_956_L23.pdf

Description

Pdf editoriale

Size

1.17 MB

Format

Unknown

Checksum (MD5)

8130187b37349851fddd70b0d0c2a744

AGILE Gamma-Ray Detection of the Exceptional GRB 221009A

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