{
  "abstract": "We present spatially resolved spectra and infer the time-delays between the multiple images of the strongly gravitationally lensed superluminous supernova (SLSN) 2025wny at z=2.015. SN 2025wny is the first known spatially resolved strongly lensed SLSN and provides a unique opportunity to measure lensing delays through the temporal evolution of supernova spectra. We present a spectroscopic dataset spanning several months, including spatially resolved spectra of images A, B, C, D, and E. We identify and measure the wavelength evolution of spectral features using Gaussian-process modeling. The time delays are inferred by jointly fitting the temporal evolution of the spectral features, yielding $Δt_{AB}=-10.3 \\pm 2.3$, $Δt_{AC}=0.1 \\pm 3.6$, $Δt_{AD}=-65.7 \\pm 3.5$, and $Δt_{AE}=3.7 \\pm 8.8$ days (68% confidence intervals). These are the among most precise time-delay measurements obtained for a lensed supernova to date, whether from spectroscopic or photometric methods. The longest delay ($Δt_{AD}$) is particularly well constrained, with a ~5% precision. Combined with the lens model presented by Mörtsell et al. (2026), the spectroscopic time-delays give a Hubble constant $H_0 = 70.2^{+8.2}_{-6.1}$ km/s/Mpc. Our analysis demonstrates that spectroscopic evolution provides an independent and complementary route to time-delay measurements in lensed supernova systems, avoiding reliance on photometric light curves alone. As future surveys discover larger samples of lensed supernovae, spectroscopic time-delay measurements will provide an important avenue for precision cosmography.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.28416",
  "author_total": 33,
  "authors": [
    {
      "name": "Joel Johansson"
    },
    {
      "name": "Edvard Mörtsell"
    },
    {
      "name": "Ariel Goobar"
    },
    {
      "name": "Steve Schulze"
    },
    {
      "name": "Maggie L. Li"
    },
    {
      "name": "Yu-Jing Qin"
    },
    {
      "name": "Lin Yan"
    },
    {
      "name": "Hannah C. Turner"
    },
    {
      "name": "Suhail Dhawan"
    },
    {
      "name": "Alice Townsend"
    },
    {
      "name": "Jakob Nordin"
    },
    {
      "name": "Aleksandra Bochenek"
    },
    {
      "name": "Malte Busmann"
    },
    {
      "name": "Kaustav K. Das"
    },
    {
      "name": "Christoffer Fremling"
    },
    {
      "name": "Lluis Galbany"
    },
    {
      "name": "Alexa C. Gordon"
    },
    {
      "name": "Daniel Gruen"
    },
    {
      "name": "Mansi M. Kasliwal"
    },
    {
      "name": "Chang Liu"
    },
    {
      "name": "Zoë McGrath"
    },
    {
      "name": "Christopher Martin"
    },
    {
      "name": "Peter Massey"
    },
    {
      "name": "Martijn S. S. L. Oei"
    },
    {
      "name": "Daniel A. Perley"
    },
    {
      "name": "Andrés I. Ponte Pérez"
    },
    {
      "name": "Francisco Prada"
    },
    {
      "name": "Nikolaus Z. Prusinski"
    },
    {
      "name": "Nabeel Rehemtulla"
    },
    {
      "name": "R. Michael Rich"
    },
    {
      "name": "Surya Shivaprasad"
    },
    {
      "name": "Jesper Sollerman"
    },
    {
      "name": "Jacob L. Wise"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cddn3w4758nnf.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.28416",
  "fulltext_url": null,
  "id": "cddn3w4758nnf",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.28416",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.CO"
    ],
    [
      "openalex",
      "3103|Gamma-ray bursts and supernovae"
    ]
  ],
  "openalex": "W7204759974",
  "pdf_url": "https://arxiv.org/pdf/2608.28416",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-28",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cddn3w4758nnf.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:22Z",
      "native_id": "2608.28416",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.28416"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    }
  ],
  "title": "Follow-up of SN 2025wny III: Spectroscopic Time-delay Measurements of a Strongly Gravitationally Lensed Superluminous Supernova",
  "title_text": "Follow-up of SN 2025wny III: Spectroscopic Time-delay Measurements of a Strongly Gravitationally Lensed Superluminous Supernova",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:22Z",
  "url": "https://research.draconitic.com/paper/cddn3w4758nnf",
  "venue": "arXiv",
  "versions": []
}