A structured jet explains the extreme GRB 221009A

Brendan O'Connor; Eleonora Troja; Geoffrey Ryan; Paz Beniamini; Hendrik van Eerten; Jonathan Granot; Simone Dichiara; Roberto Ricci; Vladimir Lipunov; James H Gillanders; Ramandeep Gill; Michael Moss; Shreya Anand; Igor Andreoni; Rosa L Becerra; David A H Buckley; Nathaniel R Butler; Stephen B Cenko; Aristarkh Chasovnikov; Joseph Durbak; Carlos Francile; Erica Hammerstein; Alexander J van der Horst; Mansi M Kasliwal; Chryssa Kouveliotou; Alexander S Kutyrev; William H Lee; Gokul P Srinivasaragavan; Vladislav Topolev; Alan M Watson; Yuhan Yang; Kirill Zhirkov

doi:10.1126/sciadv.adi1405

A structured jet explains the extreme GRB 221009A

Sci Adv. 2023 Jun 9;9(23):eadi1405. doi: 10.1126/sciadv.adi1405. Epub 2023 Jun 7.

Authors

Brendan O'Connor^{1

2

3

4}, Eleonora Troja^{5

6}, Geoffrey Ryan⁷, Paz Beniamini^{8

9}, Hendrik van Eerten¹⁰, Jonathan Granot^{1

8

9}, Simone Dichiara¹¹, Roberto Ricci^{12

13}, Vladimir Lipunov¹⁴, James H Gillanders⁵, Ramandeep Gill¹⁵, Michael Moss¹, Shreya Anand¹⁶, Igor Andreoni^{3

4

17}, Rosa L Becerra¹⁸, David A H Buckley^{19

20}, Nathaniel R Butler²¹, Stephen B Cenko^{4

17}, Aristarkh Chasovnikov¹⁴, Joseph Durbak^{3

4}, Carlos Francile^{22

23}, Erica Hammerstein³, Alexander J van der Horst¹, Mansi M Kasliwal¹⁶, Chryssa Kouveliotou¹², Alexander S Kutyrev^{3

4}, William H Lee²⁴, Gokul P Srinivasaragavan³, Vladislav Topolev¹⁴, Alan M Watson¹⁴, Yuhan Yang⁵, Kirill Zhirkov¹⁴

Affiliations

¹ Department of Physics, The George Washington University, 725 21st Street NW, Washington, DC 20052, USA.
² Astronomy, Physics and Statistics Institute of Sciences (APSIS), Washington, DC 20052, USA.
³ Department of Astronomy, University of Maryland, College Park, MD 20742-4111, USA.
⁴ Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA.
⁵ Department of Physics, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, I-00133 Rome, Italy.
⁶ INAF - Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133 Rome, Italy.
⁷ Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, ON N2L 2Y5, Canada.
⁸ Department of Natural Sciences, The Open University of Israel, P.O. Box 808, Ra'anana 4353701, Israel.
⁹ Astrophysics Research Center of the Open university (ARCO), P.O. Box 808, Ra'anana 4353701, Israel.
¹⁰ Physics Department, University of Bath, Claverton Down, Bath BA2 7AY, UK.
¹¹ The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA.
¹² Istituto Nazionale di Ricerca Metrologica, I-10135 Torino, Italy.
¹³ INAF - Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna, Italy.
¹⁴ Sternberg Astronomical Institute, Lomonosov Moscow State University, Universitetsky pr. 13, 119234 Moscow, Russia.
¹⁵ Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Antigua Carretera. a Pátzcuaro #8701, Ex-Hda. San José de la Huerta, Morelia, Michoacán, C.P. 58089, México.
¹⁶ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA.
¹⁷ Joint Space-Science Institute, University of Maryland, College Park, MD 20742, USA.
¹⁸ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510 México, CDMX, Mexico.
¹⁹ Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
²⁰ South African Astronomical Observatory, PO Box 9, 7935 Observatory, Cape Town, South Africa.
²¹ School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA.
²² Observatorio Astronomico Felix Aguilar (OAFA), San Juan 5400, Argentina.
²³ Facultad de Ciencias Exactas Fisicas y Naturales, San Juan National University, San Juan 5400, Argentina.
²⁴ Instituto de Astronomía, Universidad Nacional Autónoma de México, 04510 México, CDMX, Mexico.

Abstract

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 ≈ 10⁵⁵ 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.