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arXiv · 2507.18783

SVOM GRB 250314A at z $\simeq$ 7.3: an exploding star in the era of reionization

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. Gotz·Y. L. Qiu·S. Schanne·L. P. Xin·B. Zhang·S. N. Zhang·A. J. Nayana·L. Piro·B. Schneider·A. J. Levan·A. L. Thakur·Z. P. Zhu·G. Corcoran·N. A. Rakotondrainibe·V. D'Elia·D. Turpin·J. F. Agui Fernandez·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·Y. W. Dong·D. Dornic·P. A. E. Evans·R. A. J. Eyles-Ferris·H. Fausey·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. Thone·B. Topcu·C. W. Wang·J. Wang·Y. Wang·C. Wu·S. L. Xiong
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Abstract

Most long Gamma-ray bursts originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can be initially extremely luminous at optical/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 with the near-infrared afterglow discovery and the spectroscopic measurements of its redshift z $\simeq$ 7.3 . This burst happened when the Universe was only $\sim$ 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 optimize their identification with adapted ground follow-up observation strategies.

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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. Gotz, Y. L. Qiu, S. Schanne, L. P. Xin, B. Zhang, S. N. Zhang, A. J. Nayana, L. Piro, B. Schneider, A. J. Levan, A. L. Thakur, Z. P. Zhu, G. Corcoran, N. A. Rakotondrainibe, V. D'Elia, D. Turpin, J. F. Agui Fernandez, 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, Y. W. Dong, D. Dornic, P. A. E. Evans, R. A. J. Eyles-Ferris, H. Fausey, 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. Thone, B. Topcu, C. W. Wang, J. Wang, Y. Wang, C. Wu, S. L. Xiong. 2025-07-24. SVOM GRB 250314A at z $\simeq$ 7.3: an exploding star in the era of reionization. https://arxiv.org/abs/2507.18783

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