A1 Refereed original research article in a scientific journal
HOLISMOKES XIX: SN 2025wny at z = 2, the first strongly lensed superluminous supernova; 
Authors: Taubenberger, Stefan; Acebron, Ana; Cañameras, Raoul; Chen, Ting-Wan; Galan, Aymeric; Grillo, Claudio; Melo, Alejandra; Schuldt, Stefan; Schweinfurth, Allan G.; Suyu, Sherry H.; Aldering, Greg; Aryan, Amar; Lee, Yu-Hsing; Mamuzic, Elias; Millon, Martin; Reynolds, Thomas M.; Sergeyev, Alexey V.; Asfandiyarov, Ildar M.; Basa, Stéphane; Blondin, Stéphane; Burkhonov, Otabek A.; Christensen, Lise; Courbin, Frederic; Ehgamberdiev, Shuhrat A.; Killestein, Tom L.; Mattila, Seppo; Shaymanov, Asadulla M.; Shu, Yiping; Xu, Dong; Yang, Sheng; Gruen, Daniel; Pierel, Justin D. R.; Storfer, Christopher J.; Tran, Kim-Vy; Wong, Kenneth C.; Becerra, Rosa L.; Dornic, Damien; Ducoin, Jean-Grégoire; Globus, Noémie; Gutiérrez, Claudia P.; Jiang, Ji-an; Kuncarayakti, Hanindyo; López-Cámara, Diego; Lundqvist, Peter; Magnani, Francesco; Méndez Moreno, Enrique; Schneider, Benjamin; Vogl, Christian
Publisher: EDP Sciences
Publication year: 2026
Journal: Astronomy and Astrophysics
Article number: A365
Volume: 710
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202557847
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Open Access publication channel
Web address : https://doi.org/10.1051/0004-6361/202557847
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/527007590
Self-archived copy's licence: CC BY
Self-archived copy's version: Publisher`s PDF
We present imaging and spectroscopic observations of supernova SN 2025wny, associated with the lens candidate PS1 J0716+3821. Photometric monitoring from the Lulin and Maidanak observatories confirms multiple point-like images, consistent with SN 2025wny being strongly lensed by two foreground galaxies. Optical spectroscopy of the brightest image with the Nordic Optical Telescope and the University of Hawaii 88-inch Telescope allowed us to determine the redshift to be zSN = 2.008 ± 0.001, based on narrow absorption lines originating in the interstellar medium of the supernova host galaxy. At this redshift, SN 2025wny shows a very high rest-frame UV flux and broad spectral features even weeks after the explosion, which is consistent with superluminous supernovae of Type I. We find a high ejecta temperature and depressed spectral lines compared to other similar objects. We also measured, for the first time, the redshift of the fainter of the two lens galaxies (the ‘perturber’) to be zp = 0.375 ± 0.001, which is fully consistent with the DESI spectroscopic redshift of the main deflector at zd = 0.3754. Thus, SN 2025wny represents the first confirmed galaxy-scale strongly lensed supernova with time delays likely in the range of days to weeks, as judged from the image separations. This makes SN 2025wny suitable for cosmography, offering a promising new system for independent measurements of the Hubble constant. Following a tradition in the field of strongly lensed supernovae, we give SN 2025wny the nickname SN Winny.
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Each alphabetically ordered group of authors reflects equal contributions within the group. AA acknowledges financial support through the Beatriz Galindo programme and the project PID2022-138896NB-C51 (MCIU/AEI/MINECO/FEDER, UE), Ministerio de Ciencia, Investigación y Universidades. AM acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB 1258 – 283604770. SS has received funding from the European Union’s Horizon 2022 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 101105167 – FASTIDIoUS. We acknowledge financial support through grant PRIN-MIUR 2020SKSTHZ and from the University of Milan for the Nordic Optical Telescope programmes P68-804 and P71-804. AG, SHS and EM thank the Max Planck Society for support through the Max Planck Fellowship for SHS. This work is supported in part by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC-2094 – 390783311. MM acknowledges support by the Swiss National Science Foundation (SNSF) through return CH grant P5R5PT_225598 and Ambizione grant PZ00P2_223738. TMR is part of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140. TMR and SM acknowledge support from the Research Council of Finland project 350458. TLK acknowledges support via a Warwick Astrophysics prize post-doctoral fellowship made possible thanks to a generous philanthropic donation. TWC, AA, YHL acknowledge the financial support from the Yushan Fellow Program by the Ministry of Education, Taiwan (MOE-111-YSFMS-0008-001-P1) and the National Science and Technology Council, Taiwan (NSTC grant 114-2112-M-008-021-MY3). SY acknowledges the funding from the National Natural Science Foundation of China under grant No. 12303046, the Startup Research Fund of Henan Academy of Sciences No. 242041217, and the Joint Fund of Henan Province Science and Technology R&D Program No. 235200810057. FC acknowledges the support of the SNSF. YS acknowledges the support from the China Manned Space Program with grant no. CMS-CSST-2025-A20 and the National Natural Science Foundation of China (Grant No. 12333001). The Observatory of Maidanak team gratefully acknowledges the financial support provided by the Ministry of Higher Education, Science and Innovation of the Republic of Uzbekistan under grant No. IL-5421101855. GA wishes to acknowledge support from the United States Department of Energy, Office of Science, under Contract No. DE-AC02-05CH11231. CPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2023-151307NB-I00 SNNEXT project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. This work was supported by the “Action Thématique de Physique Stellaire” (ATPS) of CNRS/INSU PN Astro cofunded by CEA and CNES. This work alse received support by the Agencia Estatal de Investigación (AEI), Ministerio de Ciencia, Innovación y Universidades, Spain, under the project CNS2023-144016, and co-funded by the European Union – NextGenerationEU. BS acknowledges the support of the French Agence Nationale de la Recherche (ANR), under grant ANR-23-CE31-0011 (project PEGaSUS). JDRP is supported by NASA through a Einstein Fellowship grant No. HF2-51541.001 awarded by the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. JJ acknowledges the support from National Natural Science Foundation of China (Grant No. 12393811), National Key R&D Program of China (Grant No. 2023YFA1608100), the Strategic Priority Research Program of the Chinese Academy of Science (Grant No. XDB0550300), and the Japan Society for the Promotion of Science (JSPS) KAKENHI grants JP22K14069. KCW is supported by JSPS KAKENHI Grant Numbers JP24K07089, JP24H00221. This research was partly based on observations made with the Nordic Optical Telescope (programme IDs: P72-503, P68-804, and P71-804) owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The data presented here were obtained in part with ALFOSC, provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT. This publication makes use of data collected at the Lulin Observatory, which is partly supported by the TAOvA program under the NSTC grant 114-2740-M-008-002. We thank the anonymous referee for their prompt report, which helped clarify several aspects of the manuscript.
