English

Fermi-GBM Team Analysis on The Ravasio Line

High Energy Astrophysical Phenomena 2024-10-02 v1 Applications

Abstract

The prompt spectra of gamma-ray bursts are known to follow broadband continuum behavior over decades in energy. GRB 221009A, given the moniker the brightest of all time (BOAT), is the brightest gamma-ray burst identified in half a century of observations, and was first identified by the Fermi Gamma-ray Burst Monitor (GBM). On behalf of the Fermi-GBM Team, Lesage et al. (2023) described the initial GBM analysis. Ravasio et al. (2024) report the identification of a spectral line in part of the prompt emission of this burst, which they describe as evolving over 80 s from \sim12 MeV to 6 MeV. We report a GBM Team analysis on the Ravasio Line: 1) We cannot identify an instrumental effect that could have produced this signal, and 2) our method of calculating the statistical significance of the line shows it easily exceeds the 5σ\sigma discovery threshold. We additionally comment on the claim of the line beginning at earlier time intervals, up to 37 MeV, as reported in Zhang et al. (2024). We find that it is reasonable to utilize these measurements for characterization of the line evolution, with caution. We encourage theoretical studies exploring this newly discovered gamma-ray burst spectral feature, unless any rigorous alternative explanation unrelated to the emission from GRB 221009A is identified.

Keywords

Cite

@article{arxiv.2410.00286,
  title  = {Fermi-GBM Team Analysis on The Ravasio Line},
  author = {Eric Burns and Stephen Lesage and Adam Goldstein and Michael S. Briggs and Peter Veres and Suman Bala and Cuan de Barra and Elisabetta Bissaldi and William H Cleveland and Misty M Giles and Matthew Godwin and Boyan A. Hristov and C. Michelle Hui and Daniel Kocevski and Bagrat Mailyan and Christian Malacaria and Sheila McBreen and Robert Preece and Oliver J. Roberts and Lorenzo Scotton and A. von Kienlin and Colleen A. Wilson-Hodge and Joshua Wood},
  journal= {arXiv preprint arXiv:2410.00286},
  year   = {2024}
}
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