Follow-up of SN 2025wny III: Spectroscopic Time-delay Measurements of a Strongly Gravitationally Lensed Superluminous Supernova
Year: 2026
Type: preprint
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.
Source: arXiv (Cornell University)
Authors: Johansson, Joel, Mörtsell, Edvard, Goobar, Ariel, Schulze, Steve, Li, Maggie L., Qin, Yu-Jing, Yan, Lin, Turner, Hannah C., Dhawan, Suhail, Townsend, Alice, Nordin, Jakob, Bochenek, Aleksandra, Busmann, Malte, Das, Kaustav K., Fremling, Christoffer, Galbany, Lluis, Gordon, Alexa C., Gruen, Daniel, Kasliwal, Mansi M., Liu, Chang, McGrath, Zoë, Martin, Christopher, Massey, Peter, Oei, Martijn S. S. L., Perley, Daniel A., Pérez, Andrés I. Ponte, Prada, Francisco, Prusinski, Nikolaus Z., Rehemtulla, Nabeel, Rich, R. Michael, Shivaprasad, Surya, Sollerman, Jesper, Wise, Jacob L.
Institutions: University of Birmingham, Stockholm University, Weizmann Institute of Science, California Institute of Technology, Humboldt-Universität zu Berlin, Institute of Space Sciences, Institut d'Estudis Espacials de Catalunya, Northwestern University, Excellence Cluster Origins, Ludwig-Maximilians-Universität München, Liverpool John Moores University, Consejo Superior de Investigaciones Científicas, Instituto de Astrofísica de Andalucía, University of California, Los Angeles
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, W. M. Keck Foundation, California Institute of Technology, Northwestern University, Aarhus Universitet, University of Washington, Drexel University, Government of the United Kingdom, UK Research and Innovation, Institute of Science and Technology Austria, Deutsche Forschungsgemeinschaft, Swedish National Space Agency, Vetenskapsrådet, National Central University, Universitetet i Oslo, Háskóli Íslands, Turun Yliopisto, Ludwig-Maximilians-Universität München, Stockholms Universitet, Instituto de Astrofísica de Canarias, University of North Carolina at Chapel Hill, HORIZON EUROPE Framework Programme
Awards: Charting new physics with time-domain astronomy, G380733860, G4066435496, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, Gravitationally Lensed Supernovae, Collaborative Research: The Definitive Follow-up Campaign for Fast Radio Bursts, Collaborative Research: WoU-MMA: Searches After Gravitational-waves Using Arizona's Observatories (SAGUARO), Enabling Synergistic Science between the Rubin Observatory and the Zwicky Transient Facility, CAREER: Navigating the Environments of the Universe’s Fastest Transients, G6671297155, Hubble trouble: A new measure of the universal expansion using lensed supernovae, G814503682, WoU-MMA, Collaborative Research: Searches After Gravitational Waves Using Arizona's Observatories
OpenAlex ID: W7204759974