Probable evidence for a transient mega-electron volt emission line in the GRB 221023A.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40102382.
- Also identified by DOI 10.1038/s41467-025-57791-w and PMC identifier 11920065.
- Licence recorded as CC BY-NC-ND.
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Abstract
Detection of spectral line in gamma-ray bursts (GRBs) is importance for studying GRB physics, as it provides insights into the composition and physical conditions of the GRB environment. However, progress in detecting X-ray or gamma-ray emission and absorption lines in GRB spectra has been relatively slow, only the narrow emission line feature of about 10 MeV found in GRB 221009A has exhibited a significance exceeding 5σ. Here, we report the probable evidence of a narrow emission feature at about 2.1 mega-electron volts (MeV) in the spectrum of GRB 221023A. The highest statistical significance of this feature is observed in the time interval between 8 and 30 seconds after Fermi Gamma-Ray Burst Monito trigger, with the chance probability value <2.56 × 10<sup>-5</sup> (after accounting for the look-elsewhere effect), corresponding to a Gaussian-equivalent significance >4.20σ. We interpret this festure as being generated through the de-excitation of excited electrons in the relativistic hydrogen-like high-atomic-number ions entrained in the GRB jet.