Article

The Radio to GeV Afterglow of GRB 221009A

T. LaskarDepartment of Astrophysics/IMAPP, Radboud University, P.O. Box 9010, 6500 GL, Nijmegen, The NetherlandsK. D. AlexanderR. MarguttiDepartment of Astronomy and Physics, University of California, 501 Campbell Hall, Berkeley, CA 94720-3411, USATarraneh EftekhariCenter for Interdisciplinary Exploration and Research in Astrophysics, 1800 Sherman Avenue, Evanston, IL 60201, USAR. ChornockE. BergerCenter for Astrophysics ∣ Harvard & Smithsonian, Cambridge, MA 02138, USAY. CendesCenter for Astrophysics ∣ Harvard & Smithsonian, Cambridge, MA 02138, USAA. DuerrDepartment of Physics & Astronomy, University of Utah, Salt Lake City, UT 84112, USAD. A. PerleyAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool, L3 5RF, UKM. E. RavasioDepartment of Astrophysics/IMAPP, Radboud University, P.O. Box 9010, 6500 GL, Nijmegen, The NetherlandsRyo YamazakiDepartment of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258, JapanEliot H. AyacheThe Oskar Klein Centre, Department of Astronomy, Stockholm University, AlbaNova, SE-106 91 Stockholm, SwedenThomas BarclayNASA Goddard Space Flight Center, Greenbelt, MD 20771, USARodolfo Barniol DuranDepartment of Physics and Astronomy, California State University, 6000 J Street, Sacramento, CA 95819-6041 USAShivani BhandariASTRON, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, NL-7991 PD Dwingeloo, The NetherlandsDaniel BrethauerCollin T. ChristyD. L. CoppejansDepartment of Physics, University of Warwick, Coventry, CV4 7AL, UKPaul C. DuffellDepartment of Physics and Astronomy, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907, USAWen‐fai FongCenter for Interdisciplinary Exploration and Research in Astrophysics, 1800 Sherman Avenue, Evanston, IL 60201, USAA. GombocCenter for Astrophysics and Cosmology, University of Nova Gorica, Vipavska 11c, 5270 Ajdovščina, SloveniaC. GuidorziDepartment of Physics and Earth Science, University of Ferrara, Via Saragat 1, I-44122 Ferrara, ItalyJ. A. KenneaDepartment of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USAS. KobayashiAstrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool, L3 5RF, UKA. J. LevanDepartment of Astrophysics/IMAPP, Radboud University, P.O. Box 9010, 6500 GL, Nijmegen, The NetherlandsA. P. LobanovMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyBrian D. MetzgerCenter for Computational Astrophysics, Flatiron Institute, 162 5th Ave, New York, NY 10010, USAE. RosMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyGenevieve SchroederCenter for Interdisciplinary Exploration and Research in Astrophysics, 1800 Sherman Avenue, Evanston, IL 60201, USAPeter K. G. WilliamsCenter for Astrophysics ∣ Harvard & Smithsonian, Cambridge, MA 02138, USA

2023en

ABI

Abstract

Abstract GRB 221009A ( z = 0.151) is one of the closest known long γ -ray bursts (GRBs). Its extreme brightness across all electromagnetic wavelengths provides an unprecedented opportunity to study a member of this still-mysterious class of transients in exquisite detail. We present multiwavelength observations of this extraordinary event, spanning 15 orders of magnitude in photon energy from radio to γ -rays. We find that the data can be partially explained by a forward shock (FS) from a highly collimated relativistic jet interacting with a low-density, wind-like medium. Under this model, the jet’s beaming-corrected kinetic energy ( E K ∼ 4 × 10 50 erg) is typical for the GRB population. The radio and millimeter data provide strong limiting constraints on the FS model, but require the presence of an additional emission component. From equipartition arguments, we find that the radio emission is likely produced by a small amount of mass (≲6 × 10 −7 M ⊙ ) moving relativistically (Γ ≳ 9) with a large kinetic energy (≳10 49 erg). However, the temporal evolution of this component does not follow prescriptions for synchrotron radiation from a single power-law distribution of electrons (e.g., in a reverse shock or two-component jet), or a thermal-electron population, perhaps suggesting that one of the standard assumptions of afterglow theory is violated. GRB 221009A will likely remain detectable with radio telescopes for years to come, providing a valuable opportunity to track the full lifecycle of a powerful relativistic jet.

Identifiers

DOI: 10.3847/2041-8213/acbfad

Citations and references

Cited by 20 references

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