A mega-electron volt emission line in the spectrum of a gamma-ray burst

• 成果类型: Article
• 署名作者: Ravasio, Maria Edvige; Salafia, Om Sharan; Oganesyan, Gor; Mei, Alessio; Ghirlanda, Giancarlo; Ascenzi, Stefano; Banerjee, Biswajit; Macera, Samanta; Branchesi, Marica; Jonker, Peter G.; Levan, Andrew J.; Malesani, Daniele B.; Mulrey, Katharine B.; Giuliani, Andrea; Celotti, Annalisa; Ghisellini, Gabriele
• 署名单位: Radboud University Nijmegen; Istituto Nazionale Astrofisica (INAF); Gran Sasso Science Institute (GSSI); Gran Sasso Science Institute (GSSI); Istituto Nazionale di Fisica Nucleare (INFN); Autonomous University of Barcelona; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - Instituto de Ciencias del Espacio (ICE); Institut d'Estudis Espacials de Catalunya (IEEC); University of Warwick; University of Copenhagen; Niels Bohr Institute; Istituto Nazionale Astrofisica (INAF); International School for Advanced Studies (SISSA)
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-11812
• DOI: 10.1126/science.adj3638
• 发表日期: 2024-07-26
• 页码: 452-455
• 关键词: afterglow; absorption; features; search; grb; DISCOVERY; radiation; cyclotron; models; ejecta

摘要

A long gamma-ray burst (GRB) is observed when the collapse of a massive star produces an ultrarelativistic outflow pointed toward Earth. Gamma-ray spectra of long GRBs are smooth, typically modeled by joint power-law segments describing a continuum, with no detected spectral lines. We report a significant (>6 sigma) narrow emission feature at similar to 10 mega-electron volts (MeV) in the spectrum of the bright GRB 221009A. Over 80 seconds, it evolves in energy (similar to 12 to similar to 6 MeV) and in luminosity (similar to 1.1 to <0.43 x 10(50) erg second(-1)) but has a constant width of similar to 1 MeV. We interpret this feature as a blueshifted spectral line produced by the annihilation of electron-positron pairs, potentially in the same location responsible for emitting the brightest GRB pulses.