A structured jet explains the extreme GRB 221009A.
Brendan O'ConnorEleonora TrojaGeoffrey RyanPaz BeniaminiHendrik van EertenJonathan GranotSimone DichiaraRoberto RicciVladimir LipunovJames H GillandersRamandeep GillMichael MossShreya AnandIgor AndreoniRosa L BecerraDavid A H BuckleyNathaniel R ButlerS Bradley CenkoAristarkh ChasovnikovJoseph DurbakCarlos FrancileErica HammersteinAlexander J van der HorstMansi M KasliwalChryssa KouveliotouAlexander S KutyrevWilliam H LeeGokul P SrinivasaragavanVladislav TopolevAlan M WatsonYu-Han YangKirill ZhirkovPublished in: Science advances (2023)
Long-duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far the brightest burst ever observed. Because of its enormous energy ( E iso ≈ 10 55 erg) and proximity ( z ≈ 0.15), GRB 221009A is an exceptionally rare event that pushes the limits of our theories. We present multiwavelength observations covering the first 3 months of its afterglow evolution. The x-ray brightness decays as a power law with slope ≈ t -1.66 , which is not consistent with standard predictions for jetted emission. We attribute this behavior to a shallow energy profile of the relativistic jet. A similar trend is observed in other energetic GRBs, suggesting that the most extreme explosions may be powered by structured jets launched by a common central engine.