{ "abstract": "We present a multiwavelength study of GRB 260310A, a nearby long-duration gamma-ray burst (GRB) at z ≃ 0.153 associated with a broad-lined Type Ic supernova. Despite its modest prompt gamma-ray output, E γ ,iso ≃ 3.5 × 10 ⁵⁰ erg, GRB 260310A exhibits one of the brightest afterglows ever observed in the X-ray, optical, and radio bands. Its apparent brightness is not its only remarkable feature. The optical afterglow displays a delayed onset, characterized by a slow rising phase, with slope α ≈ −1, and a late peak at ∼0.1 day. We argue that the combination of weak prompt emission, hard peak energy, and late afterglow onset is naturally explained by a GRB jet viewed off-axis. The radio spectral energy distributions are consistent with synchrotron radiation and indicate the presence of both reverse- shock (RS) and forward-shock (FS) components, thus providing a first test of RS models in an off-axis geometry. The X-ray afterglow displays a prominent rebrightening, monitored for up to ∼68 days with no evidence of spectral evolution. A low level of linear polarization, Π ≈ 1.7%, is measured at 15 GHz at T ₀ + 55 days and suggests that, at these late times, the FS is the dominant emission component from radio to X-rays. This late-time rebrightening represents a critical test for the two-component jet model. If interpreted as the emergence of a narrow jet core viewed further off-axis, it would imply extreme luminosities and energetics for an on-axis observer.", "abstract_shown": true, "affiliations": [ "University of Rome “Tor Vergata”", "INAF—Istituto di Radioastronomia", "The University of Hong Kong", "Instituto de Astrofísica de Andalucía (IAA-CSIC)", "Carnegie Mellon University", "University of Rome “Sapienza”", "Universidad de Málaga", "University of Bath", "The Pennsylvania State University", "INAF—Italian Centre for Astronomical Archives c/o Osservatorio Astronomico di Trieste", "Ludwig-Maximilians-Universität München", "Excellence Cluster ORIGINS", "Petro Mohyla Black Sea National University", "Universidad Nacional Autónoma de México (IA-UNAM)", "Guangxi University", "Czech Academy of Sciences", "NASA", "University of Maryland", "Masaryk University Brno", "Aryabhatta Research Institute of Observational Sciences (ARIES)", "URSA Astronomical Association" ], "article_type": null, "arxiv": null, "author_total": 34, "authors": [ { "affs": [ 0 ], "name": "Yu-Han Yang", "orcid": "0000-0003-0691-6688" }, { "affs": [ 0, 1 ], "name": "Roberto Ricci", "orcid": "0000-0003-4631-1528" }, { "affs": [ 0 ], "name": "Eleonora Troja", "orcid": "0000-0002-1869-7817" }, { "affs": [ 0 ], "name": "Muskan Yadav", "orcid": "0009-0004-9520-5822" }, { "affs": [ 2 ], "name": "Yi-Han Iris Yin", "orcid": "0000-0002-5596-5059" }, { "affs": [ 3 ], "name": "Rubén Sánchez-Ramírez", "orcid": "0000-0002-7158-5099" }, { "affs": [ 4 ], "name": "Brendan O’Connor", "orcid": "0000-0002-9700-0036" }, { "affs": [ 0, 5 ], "name": "Niccolò Passaleva", "orcid": "0009-0007-6886-4082" }, { "affs": [ 3, 6 ], "name": "Alberto J. Castro-Tirado", "orcid": "0000-0003-2999-3563" }, { "affs": [ 7 ], "name": "Hendrik van Eerten", "orcid": "0000-0002-8680-8718" }, { "affs": [ 8 ], "name": "Simone Dichiara", "orcid": "0000-0001-6849-1270" }, { "affs": [ 1, 9 ], "name": "Vincenzo Galluzzi", "orcid": "0000-0003-1394-7044" }, { "affs": [ 0 ], "name": "Narjes Shahamat Dehsorkh", "orcid": "0009-0009-7526-4522" }, { "affs": [ 3 ], "name": "Iván Agudo", "orcid": "0000-0002-3777-6182" }, { "affs": [ 3 ], "name": "Jesús Aceituno", "orcid": "0000-0003-0487-1105" }, { "affs": [ 10, 11 ], "name": "Malte Busmann", "orcid": "0009-0001-0574-2332" }, { "affs": [ 3 ], "name": "Maria D. Caballero-García", "orcid": "0000-0001-7920-4564" }, { "affs": [ 3 ], "name": "Emilio Fernández-García", "orcid": "0009-0009-4604-9639" }, { "affs": [ 10, 11 ], "name": "Daniel Gruen", "orcid": "0000-0003-3270-7644" }, { "affs": [ 3 ], "name": "Maria Gritsevich", "orcid": "0000-0003-4268-6277" }, { "affs": [ 3, 12 ], "name": "Sergiy Guziy", "orcid": "0000-0003-2628-6468" }, { "affs": [ 13 ], "name": "David Hiriart", "orcid": "0000-0002-4711-7658" }, { "affs": [ 14 ], "name": "You-Dong Hu", "orcid": "0000-0002-7400-4608" }, { "affs": [ 15 ], "name": "Martin Jelínek", "orcid": "0000-0003-3922-7416" }, { "affs": [ 16, 17 ], "name": "Alexander Kutyrev", "orcid": "0000-0002-2715-8460" }, { "affs": [ 15 ], "name": "Alzbeta Malenakova", "orcid": "0000-0002-0636-9138" }, { "affs": [ 15, 18 ], "name": "Filip Novotny", "orcid": "0009-0008-5788-3584" }, { "affs": [ 3 ], "name": "Ignacio Pérez-García", "orcid": "0000-0002-7273-3671" }, { "affs": [ 19 ], "name": "Shashi B. Pandey", "orcid": "0000-0002-1474-1980" }, { "affs": [ 20 ], "name": "Jorma Ryske", "orcid": "0009-0009-4453-8260" }, { "affs": [ 3 ], "name": "Alfredo Sota", "orcid": "0000-0002-9404-6952" }, { "affs": [ 15 ], "name": "Jan Strobl", "orcid": "0000-0002-4147-2878" }, { "affs": [ 0, 5 ], "name": "Hira Waseem", "orcid": "0009-0001-2089-9899" }, { "affs": [ 3 ], "name": "Siyu Wu", "orcid": "0009-0004-7113-8258" } ], "bibtex": "https://research.draconitic.com/paper/drrc5ck7q8pm7.bib", "cited_by": 0, "doi": "10.3847/2041-8213/aea990", "fulltext_url": null, "id": "drrc5ck7q8pm7", "issns": [ "2041-8213", "2041-8205" ], "landing_url": "https://iopscience.iop.org/article/10.3847/2041-8213/aea990", "language": null, "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "feed-journal", "astronomy/general" ], [ "openalex", "3103|Gamma-ray bursts and supernovae" ] ], "openalex": "W7162287227", "pdf_url": "https://iopscience.iop.org/article/10.3847/2041-8213/aea990/pdf", "pmcid": null, "pmid": null, "published": "2026-10-28", "publisher": "American Astronomical Society", "ris": "https://research.draconitic.com/paper/drrc5ck7q8pm7.ris", "sources": [ { "first_seen": "2026-10-30T12:17:17Z", "native_id": "10.3847/2041-8213/aea990", "source": "feed-iop", "url": "https://iopscience.iop.org/article/10.3847/2041-8213/aea990" }, { "first_seen": "2026-10-30T12:18:13Z", "native_id": "10.3847/2041-8213/aea990", "source": "crossref", "url": "https://iopscience.iop.org/article/10.3847/2041-8213/aea990" } ], "subjects": [ { "field": "astronomy", "origin": "openalex:3103|Gamma-ray bursts and supernovae", "subfield": "high-energy-astrophysics" } ], "title": "An Extremely Bright Slow-rising Afterglow from an Off-axis Jet in GRB 260310A", "title_text": "An Extremely Bright Slow-rising Afterglow from an Off-axis Jet in GRB 260310A", "type": "peer-reviewed", "updated_at": "2026-10-30T12:18:13Z", "url": "https://research.draconitic.com/paper/drrc5ck7q8pm7", "venue": "The Astrophysical Journal Letters", "versions": [] }