The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151

D. B. Malesani; A. J. Levan; L. Izzo; A. De Ugarte Postigo; G. Ghirlanda; K. E. Heintz; D. A. Kann; G. P. Lamb; J. Palmerio; O. S. Salafia; R. Salvaterra; N. R. Tanvir; J. F. Agüí Fernández; S. Campana; A. A. Chrimes; Avanzo P D Avanzo P; Elia V D Elia V; M. Della Valle; M. De Pasquale; J. P.U. Fynbo; N. Gaspari; B. P. Gompertz; D. H. Hartmann; J. Hjorth; P. Jakobsson; E. Palazzi; E. Pian; G. Pugliese; M. E. Ravasio; A. Rossi; A. Saccardi; P. Schady; B. Schneider; J. Sollerman; R. L.C. Starling; C. C. Thöne; A. J. Van Der Horst; S. D. Vergani; D. Watson; K. Wiersema; D. Xu; T. Zafar; S. Y. Zheng

doi:10.1051/0004-6361/202346146

The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151

D. B. Malesani
, A. J. Levan
, L. Izzo
, A. De Ugarte Postigo
, G. Ghirlanda
, K. E. Heintz
, D. A. Kann
, G. P. Lamb
, J. Palmerio
, O. S. Salafia
, R. Salvaterra
, N. R. Tanvir
, J. F. Agüí Fernández
, S. Campana
, A. A. Chrimes
, Avanzo P D Avanzo P
, Elia V D Elia V
, M. Della Valle
, M. De Pasquale
, J. P.U. Fynbo

N. Gaspari, B. P. Gompertz, D. H. Hartmann, J. Hjorth, P. Jakobsson, E. Palazzi, E. Pian, G. Pugliese, M. E. Ravasio, A. Rossi, A. Saccardi, P. Schady, B. Schneider, J. Sollerman, R. L.C. Starling, C. C. Thöne, A. J. Van Der Horst, S. D. Vergani, D. Watson, K. Wiersema, D. Xu, T. Zafar, S. Y. Zheng

Radboud University Nijmegen
Cosmic Dawn Center
University of Copenhagen
University of Warwick
Université Côte d'Azur
INAF - Osservatorio Astronomico di Brera
Infn - Sezione di Milano-Bicocca
Johann Wolfgang Goethe-Universitat Frankfurt am Main
Liverpool John Moores University
PSL Research University
INAF Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan
University of Leicester
Instituto de Astrofisica de Andalucia
European Space Research and Technology Centre
Space Science Data Center (SSDC) - Agenzia Spaziale Italiana (ASI)
INAF - Osservatorio Astronomico di Capodimonte
University of Messina
University of Birmingham
Clemson University
University of Iceland
INAF-Istituto di Astrofisica e Planetologia Spaziali
University of Amsterdam
MIT Kavli Institute for Astrophysics and Space Research
Stockholm University
Academy of Sciences of the Czech Republic
George Washington University
Lancaster University
Chinese Academy of Sciences
Macquarie University

Research output: Contribution to journal › Article › peer-review

6 Citations (SciVal)

Abstract

Context. The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons, thus effective probes of the distant Universe. The most luminous bursts are typically detected at moderate and high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as those at TeV energies. Aims. Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date, with emission extending well into the TeV regime. Methods. We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-infrared (NIR) spectroscopy of the burst afterglow 0.5 days after the explosion. Results. The spectra exhibit both absorption and emission lines from material in a host galaxy at zGRB = 0.15095 ± 0.00005. Thus, GRB 221009A was a relatively nearby burst with a luminosity distance of dL = 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of long GRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, Eiso > 5 × 1054 erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades and once per millennium.

Original language	English
Article number	A134
Journal	Astronomy and Astrophysics
Volume	701
Early online date	1 Sept 2025
DOIs	https://doi.org/10.1051/0004-6361/202346146
Publication status	Published - 1 Sept 2025

Acknowledgements

We dedicate this paper to the memory of our beloved colleagues David Alexander “Alex” Kann, who was especially fond of this unique GRB. We are grateful for a constructive report from an anonymous referee. This paper is based on observations collected at the European Southern Observatory under ESO programme 110.24CF (PI Tanvir). We thank the support from the ESO observing staff in Paranal, in particular Cédric Ledoux, Matias Jones, Michael Abdul-Masih, Zahed Wahhaj. PDA acknowledge funding from the Italian Space Agency, contract ASI/INAF n. I/004/11/4 and from PRIN-MIUR 2017 (grant 20179ZF5KS). DAK acknowledges the support by the State of Hessen within the Research Cluster ELEMENTS (Project ID 500/10.006). DBM, AJL and NRT are supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 725246). The Cosmic Dawn Center is supported by the Danish National Research Foundation. JH and LI were supported by a VILLUM FONDEN Investigator grant (project number 16599). EPi acknowledges financial support through an INAF research grant. MER acknowledges support from the research programme Athena with project number 184.034.002, which is financed by the Dutch Research Council (NWO). AS and SDV acknowledge support from DIM-ACAV+. KW acknowledges support through a UK Research and Innovation Future Leaders Fellowship awarded to Dr. B. Simmons (MR/T044136/1). DX acknowledges the science research grants from the China Manned Space Project with NO. CMS-CSST-2021-A13 and CMS-CSST-2021-B11.

Keywords

Gamma-ray burst: general
Gamma-ray burst: individual: GRB 221009A

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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Cite this

Malesani, D. B., Levan, A. J., Izzo, L., De Ugarte Postigo, A., Ghirlanda, G., Heintz, K. E., Kann, D. A., Lamb, G. P., Palmerio, J., Salafia, O. S., Salvaterra, R., Tanvir, N. R., Agüí Fernández, J. F., Campana, S., Chrimes, A. A., D Avanzo P, A. P., D Elia V, E. V., Della Valle, M., De Pasquale, M., ... Zheng, S. Y. (2025). The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151. Astronomy and Astrophysics, 701, Article A134. https://doi.org/10.1051/0004-6361/202346146

Malesani, DB, Levan, AJ, Izzo, L, De Ugarte Postigo, A, Ghirlanda, G, Heintz, KE, Kann, DA, Lamb, GP, Palmerio, J, Salafia, OS, Salvaterra, R, Tanvir, NR, Agüí Fernández, JF, Campana, S, Chrimes, AA, D Avanzo P, AP, D Elia V, EV, Della Valle, M, De Pasquale, M, Fynbo, JPU, Gaspari, N, Gompertz, BP, Hartmann, DH, Hjorth, J, Jakobsson, P, Palazzi, E, Pian, E, Pugliese, G, Ravasio, ME, Rossi, A, Saccardi, A, Schady, P, Schneider, B, Sollerman, J, Starling, RLC, Thöne, CC, Van Der Horst, AJ, Vergani, SD, Watson, D, Wiersema, K, Xu, D, Zafar, T & Zheng, SY 2025, 'The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151', Astronomy and Astrophysics, vol. 701, A134. https://doi.org/10.1051/0004-6361/202346146

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title = "The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151",

abstract = "Context. The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons, thus effective probes of the distant Universe. The most luminous bursts are typically detected at moderate and high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as those at TeV energies. Aims. Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date, with emission extending well into the TeV regime. Methods. We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-infrared (NIR) spectroscopy of the burst afterglow 0.5 days after the explosion. Results. The spectra exhibit both absorption and emission lines from material in a host galaxy at zGRB = 0.15095 ± 0.00005. Thus, GRB 221009A was a relatively nearby burst with a luminosity distance of dL = 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of long GRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, Eiso > 5 × 1054 erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades and once per millennium.",

keywords = "Gamma-ray burst: general, Gamma-ray burst: individual: GRB 221009A",

author = "Malesani, \{D. B.\} and Levan, \{A. J.\} and L. Izzo and \{De Ugarte Postigo\}, A. and G. Ghirlanda and Heintz, \{K. E.\} and Kann, \{D. A.\} and Lamb, \{G. P.\} and J. Palmerio and Salafia, \{O. S.\} and R. Salvaterra and Tanvir, \{N. R.\} and \{Ag{\"u}{\'i} Fern{\'a}ndez\}, \{J. F.\} and S. Campana and Chrimes, \{A. A.\} and \{D Avanzo P\}, \{Avanzo P\} and \{D Elia V\}, \{Elia V\} and \{Della Valle\}, M. and \{De Pasquale\}, M. and Fynbo, \{J. P.U.\} and N. Gaspari and Gompertz, \{B. P.\} and Hartmann, \{D. H.\} and J. Hjorth and P. Jakobsson and E. Palazzi and E. Pian and G. Pugliese and Ravasio, \{M. E.\} and A. Rossi and A. Saccardi and P. Schady and B. Schneider and J. Sollerman and Starling, \{R. L.C.\} and Th{\"o}ne, \{C. C.\} and \{Van Der Horst\}, \{A. J.\} and Vergani, \{S. D.\} and D. Watson and K. Wiersema and D. Xu and T. Zafar and Zheng, \{S. Y.\}",

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doi = "10.1051/0004-6361/202346146",

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TY - JOUR

T1 - The brightest GRB ever detected

T2 - GRB 221009A as a highly luminous event at z=0.151

AU - Malesani, D. B.

AU - Levan, A. J.

AU - Izzo, L.

AU - De Ugarte Postigo, A.

AU - Ghirlanda, G.

AU - Heintz, K. E.

AU - Kann, D. A.

AU - Lamb, G. P.

AU - Palmerio, J.

AU - Salafia, O. S.

AU - Salvaterra, R.

AU - Tanvir, N. R.

AU - Agüí Fernández, J. F.

AU - Campana, S.

AU - Chrimes, A. A.

AU - D Avanzo P, Avanzo P

AU - D Elia V, Elia V

AU - Della Valle, M.

AU - De Pasquale, M.

AU - Fynbo, J. P.U.

AU - Gaspari, N.

AU - Gompertz, B. P.

AU - Hartmann, D. H.

AU - Hjorth, J.

AU - Jakobsson, P.

AU - Palazzi, E.

AU - Pian, E.

AU - Pugliese, G.

AU - Ravasio, M. E.

AU - Rossi, A.

AU - Saccardi, A.

AU - Schady, P.

AU - Schneider, B.

AU - Sollerman, J.

AU - Starling, R. L.C.

AU - Thöne, C. C.

AU - Van Der Horst, A. J.

AU - Vergani, S. D.

AU - Watson, D.

AU - Wiersema, K.

AU - Xu, D.

AU - Zafar, T.

AU - Zheng, S. Y.

PY - 2025/9/1

Y1 - 2025/9/1

N2 - Context. The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons, thus effective probes of the distant Universe. The most luminous bursts are typically detected at moderate and high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as those at TeV energies. Aims. Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date, with emission extending well into the TeV regime. Methods. We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-infrared (NIR) spectroscopy of the burst afterglow 0.5 days after the explosion. Results. The spectra exhibit both absorption and emission lines from material in a host galaxy at zGRB = 0.15095 ± 0.00005. Thus, GRB 221009A was a relatively nearby burst with a luminosity distance of dL = 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of long GRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, Eiso > 5 × 1054 erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades and once per millennium.

AB - Context. The extreme luminosity of gamma-ray bursts (GRBs) makes them powerful beacons, thus effective probes of the distant Universe. The most luminous bursts are typically detected at moderate and high redshift, where the volume for seeing such rare events is maximized and the star-formation activity is greater than at z = 0. For distant events, not all observations are feasible, such as those at TeV energies. Aims. Here we present a spectroscopic redshift measurement for the exceptional GRB 221009A, the brightest GRB observed to date, with emission extending well into the TeV regime. Methods. We used the X-shooter spectrograph at the ESO Very Large Telescope (VLT) to obtain simultaneous optical to near-infrared (NIR) spectroscopy of the burst afterglow 0.5 days after the explosion. Results. The spectra exhibit both absorption and emission lines from material in a host galaxy at zGRB = 0.15095 ± 0.00005. Thus, GRB 221009A was a relatively nearby burst with a luminosity distance of dL = 745 Mpc. Its host galaxy properties (star-formation rate and metallicity) are consistent with those of long GRB hosts at low redshift. This redshift measurement yields information on the energy of the burst. The inferred isotropic energy release, Eiso > 5 × 1054 erg, lies at the high end of the distribution, making GRB 221009A one of the nearest and also most energetic GRBs observed to date. We estimate that such a combination (nearby as well as intrinsically bright) occurs between once every few decades and once per millennium.

KW - Gamma-ray burst: general

KW - Gamma-ray burst: individual: GRB 221009A

UR - https://www.scopus.com/pages/publications/105033159428

U2 - 10.1051/0004-6361/202346146

DO - 10.1051/0004-6361/202346146

M3 - Article

AN - SCOPUS:105033159428

SN - 0004-6361

VL - 701

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A134

ER -

The brightest GRB ever detected: GRB 221009A as a highly luminous event at z=0.151

Abstract

Acknowledgements

Keywords

ASJC Scopus subject areas

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