SVOM GRB 250314A at z ≃ 7.3: An exploding star in the era of re-ionization

B. Cordier; J. Y. Wei; N. R. Tanvir; S. D. Vergani; D. B. Malesani; J. P. U. Fynbo; A. de Ugarte Postigo; A. Saccardi; F. Daigne; J.-L. Atteia; O. Godet; D. Götz; Y. L. Qiu; S. Schanne; L. P. Xin; B. Zhang; S. N. Zhang; A. J. Nayana; L. Piro; H. Fausey; B. Schneider; A. J. Levan; A. L. Thakur; Z. P. Zhu; G. Corcoran; N. A. Rakotondrainibe; V. D’Elia; D. Turpin; J. F. Agüí Fernández; M. A. Aloy; J. An; M. Bai; S. Basa; M. G. Bernardini; A. Bochenek; R. Brivio; M. Brunet; G. Bruni; S. B. Cenko; Q. Cheng; A. Chrimes; L. Christensen; A. Claret; A. Coleiro; L. Cotter; S. Crepaldi; J. S. Deng; Dimple Dimple; Y. W. Dong; D. Dornic; P. A. Evans; R. A. J. Eyles-Ferris; M. Ferro; L. Galbany; M. Garnichey; G. Gianfagna; B. P. Gompertz; H. Goto; N. Habeeb; P. Y. Han; X. H. Han; D. H. Hartmann; K. E. Heintz; J. Y. Hu; M. H. Huang; L. Izzo; P. Jakobsson; J. A. Kennea; C. Lachaud; T. Laskar; D. Li; H. L. Li; R. Z. Li; X. Liu; Y. Liu; G. Lombardi; H. Louvin; P. Maggi; T. Maiolino; Q. Y. Mao; A. Martin-Carrillo; K. Mercier; P. O’Brien; J. T. Palmerio; P. Petitjean; D. L. A. Pieterse; F. Piron; G. Pugliese; B. C. Rayson; T. Reynolds; F. Robinet; A. Rossi; R. Salvaterra; C. C. Thöne; B. Topçu; C. W. Wang; J. Wang; Y. Wang; C. Wu; S. L. Xiong; D. Xu; H. N. Yang; W. M. Yuan; Y. H. Zhang; X. F. Zhang; S. J. Zheng

doi:10.1051/0004-6361/202556580

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Volume 704 (December 2025)

A&A, 704 (2025) L7

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Issue		A&A Volume 704, December 2025


Article Number		L7
Number of page(s)		13
Section		Letters to the Editor
DOI		https://doi.org/10.1051/0004-6361/202556580
Published online		09 December 2025

A&A, 704, L7 (2025)

Letter to the Editor

SVOM GRB 250314A at z ≃ 7.3: An exploding star in the era of re-ionization

B. Cordier¹^⋆, J. Y. Wei²^,3^⋆, N. R. Tanvir⁴^⋆, S. D. Vergani⁵^,6, D. B. Malesani⁷^,8^,9, J. P. U. Fynbo⁷^,8, A. de Ugarte Postigo¹⁰, A. Saccardi¹¹, F. Daigne⁶, J.-L. Atteia¹², O. Godet¹², D. Götz¹¹, Y. L. Qiu², S. Schanne¹, L. P. Xin², B. Zhang¹³^,14, S. N. Zhang¹⁵, A. J. Nayana¹⁶, L. Piro¹⁷, H. Fausey¹⁸, B. Schneider¹⁰, A. J. Levan⁹^,19, A. L. Thakur¹⁷, Z. P. Zhu², G. Corcoran²⁰, N. A. Rakotondrainibe¹⁰, V. D’Elia²¹, D. Turpin¹¹, J. F. Agüí Fernández²², M. A. Aloy²³^,24, J. An², M. Bai²⁵, S. Basa¹⁰, M. G. Bernardini²⁶^,27, A. Bochenek²⁸, R. Brivio²⁶, M. Brunet¹², G. Bruni¹⁷, S. B. Cenko²⁹, Q. Cheng², A. Chrimes³⁰^,9, L. Christensen⁷^,8, A. Claret¹, A. Coleiro³¹, L. Cotter²⁰, S. Crepaldi³², J. S. Deng²^,3, Dimple³³, Y. W. Dong¹⁵, D. Dornic³⁴, P. A. Evans⁴, R. A. J. Eyles-Ferris⁴, M. Ferro²⁶, L. Galbany³⁵^,36, M. Garnichey⁵, G. Gianfagna¹⁷, B. P. Gompertz³³, H. Goto³⁷^,11, N. Habeeb⁴, P. Y. Han³⁸, X. H. Han², D. H. Hartmann³⁹, K. E. Heintz⁷^,8, J. Y. Hu², M. H. Huang², L. Izzo⁴⁰^,41, P. Jakobsson⁴², J. A. Kennea⁴³, C. Lachaud³¹, T. Laskar⁴⁴, D. Li⁴⁵, H. L. Li², R. Z. Li⁴⁶, X. Liu², Y. Liu²⁵, G. Lombardi⁴⁷^,48^,49, H. Louvin¹, P. Maggi⁵⁰, T. Maiolino²⁷, Q. Y. Mao⁴⁵, A. Martin-Carrillo²⁰, K. Mercier³², P. O’Brien⁴, J. T. Palmerio¹¹, P. Petitjean⁶, D. L. A. Pieterse⁹, F. Piron²⁷, G. Pugliese⁵¹, B. C. Rayson⁴, T. Reynolds⁷^,8, F. Robinet⁵², A. Rossi⁵³, R. Salvaterra⁵⁴, C. C. Thöne⁵⁵, B. Topçu⁵⁶, C. W. Wang¹⁵, J. Wang², Y. Wang⁵⁷, C. Wu², S. L. Xiong¹⁵, D. Xu², H. N. Yang², W. M. Yuan², Y. H. Zhang⁴⁵, X. F. Zhang⁴⁶ and S. J. Zheng¹⁵

¹ CEA Paris-Saclay, Irfu/Département d’Astrophysique, 91191 Gif sur Yvette, France
² National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
³ School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 101408, China
⁴ School of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
⁵ UX, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Meudon 92190, France
⁶ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, F-75014 Paris, France
⁷ Niels Bohr Institute, University of Copenhagen, Jagtvej 155, 2200 Copenhagen N, Denmark
⁸ The Cosmic Dawn Centre (DAWN), Denmark
⁹ Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010 Nijmegen 6500 GL, The Netherlands
¹⁰ Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
¹¹ Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191 Gif-sur-Yvette, France
¹² IRAP, Université de Toulouse, CNRS, CNES, Toulouse, France
¹³ Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong, China
¹⁴ Nevada Center for Astrophysics and Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154, USA
¹⁵ Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
¹⁶ Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA
¹⁷ INAF, Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, Roma 00133, Italy
¹⁸ Department of Physics and Astronomy, Baylor University, One Bear Place #97316, Waco, TX 76798, USA
¹⁹ Department of Physics, University of Warwick, Coventry CV4 7AL, UK
²⁰ School of Physics and Centre for Space Research, University College Dublin, Belfield, Dublin D04 V1W8, Ireland
²¹ Space Science Data Center (SSDC), Agenzia Spaziale Italiana (ASI), Roma I-00133, Italy
²² Centro Astronòmico Hispano en Andalucìa, Observatorio de Calar Alto, Sierra de los Filabres, Gèrgal, Almerìa 04550, Spain
²³ Departament d’Astonomia i Astrofìsica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot (València), Spain
²⁴ Obs. Astronòmic, Universitat de València, 46980 Paterna, Spain
²⁵ National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
²⁶ INAF – Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate, LC, Italy
²⁷ Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3, F-34095 Montpellier, France
²⁸ Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom
²⁹ Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771, USA
³⁰ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
³¹ Université Paris Cité, CNRS, Astroparticule et Cosmologie, F-75013 Paris, France
³² Centre National d’Etudes Spatiales, Centre Spatial de Toulouse, Toulouse Cedex 9, France
³³ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
³⁴ Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France
³⁵ Institut d’Estudis Espacials de Catalunya (IEEC), E-08034 Barcelona, Spain
³⁶ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
³⁷ College of Science and Engineering, School of Mathematics and Physics, Kanazawa University, Kakuma, Kanazawa, 9201192 Ishikawa, Japan
³⁸ Department of Astronomy, School of Physics, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, PR China
³⁹ Department of Physics & Astronomy, Clemson University, Clemson, SC 29634, USA
⁴⁰ INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80121 Naples, Italy
⁴¹ DARK, Niels Bohr Institute, University of Copenhagen, Jagtvej 155A, 2200 Copenhagen, Denmark
⁴² Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik, Iceland
⁴³ Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA
⁴⁴ Department of Physics & Astronomy, University of Utah, Salt Lake City, UT 84112, USA
⁴⁵ Key Lab for Satellite Digitalization Technology, Innovation Academy for Microsatellites, Chinese Academy of Sciences, No. 1 Xueyang Road, Shanghai 201304, China
⁴⁶ Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China
⁴⁷ GRANTECAN S.A., Cuesta de San José s/n, E-38712 Breña Baja, La Palma, Spain
⁴⁸ Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain
⁴⁹ Royal Commission for AlUla, Riyadh, Saudi Arabia
⁵⁰ Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, 11 rue de l’Université, F-67000 Strasbourg, France
⁵¹ Anton Pannekoek Institute of Astronomy, University of Amsterdam, P.O. Box 94249 1090 GE Amsterdam, The Netherlands
⁵² Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
⁵³ Osservatorio di Astrofisica e Scienza dello Spazio, INAF, Via Piero Gobetti 93/3, Bologna 40129, Italy
⁵⁴ INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, Via A. Corti 12, 20133 Milano, Italy
⁵⁵ E. Kharadze Georgian National Astrophysical Observatory, Mt. Kanobili, Abastumani 0301, Adigeni, Georgia
⁵⁶ Departmant of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
⁵⁷ Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China

^⋆ Corresponding authors: bertrand.cordier@cea.fr; wjy@nao.cas.cn; nrt3@leicester.ac.uk

Received: 24 July 2025
Accepted: 28 September 2025

Abstract

Most long gamma-ray bursts (LGRBs) originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can initially be extremely luminous at optical and near-infrared wavelengths, making them detectable at large cosmological distances. Here we report the detection and observations of GRB 250314A by the SVOM satellite and the subsequent follow-up campaign that led to the discovery of the near-infrared afterglow and spectroscopic measurements of its redshift z ≃ 7.3. This burst occurred when the Universe was only about 5% of its current age. We discuss the signature of these rare events within the context of the SVOM operating model and the ways to optimise their identification with adapted ground follow-up observation strategies.

Key words: gamma-ray burst: general / galaxies: high-redshift / gamma-ray burst: individual: GRB250314A

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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