SN Helios: A Multiply Imaged Type II Supernova Opening Time-Delay Cosmography beyond redshift of 3
Year: 2026
Type: preprint
Abstract: We report the discovery and spectroscopic confirmation of SN Helios, a strongly lensed, multiply imaged Type II supernova (SN) at $z=3.34$ behind the galaxy cluster RXC J0018.5+1626. The transient was identified as a red F150W-dropout source (F277W = 26.1 mag) in JWST/NIRCam imaging taken on 2026 July 3 for the VENUS survey, with no counterpart in 2024 December imaging. Director's Discretionary Time observations on 2026 August 17 added second-epoch NIRCam imaging and a deep NIRSpec prism spectrum. The spectrum shows a strong, spectrally resolved H$α$ emission line (FWHM $\approx 7900$ km/s) with a P-Cygni absorption blueshifted by 8800 km/s, together with corresponding H$β$ and He I $λ$10830 features, establishing a hydrogen-rich photosphere at $z=3.34$. Template fits classify SN Helios as a Type II SN, and light-curve comparisons with well-studied local SNe II yield a phase of $27.5\pm2.8$ rest-frame days past B-band maximum. Independent cluster lens models magnify the observed image by $μ\approx 10$-20 and predict another image within $\simeq 2$-6 yr, offering a rare opportunity for a time-delay measurement of $H_{0}$ with a source at $z>3$. The host galaxy is undetected in deep rest-frame ultraviolet and optical imaging, in emission lines, and in ALMA 2 mm dust continuum, leaving a heavily obscured counterpart unlikely. Its de-lensed $M_{\rm UV}\gtrsim -13$ places it far below blank-field limits and adds support to an elevated core-collapse rate per unit star formation in ultra-faint galaxies. Without the multi-epoch data, SN Helios would masquerade as a convincing $z\approx 16$ Lyman-break galaxy, with galaxy-template fits strongly disfavoring any low-redshift solution even with multiple medium bands. Its spectrum thus provides an empirical SED template with which high-redshift searches can vet similar dropout candidates.
Source: arXiv (Cornell University)
Authors: Fujimoto, Seiji, Larison, Conor, Pierel, Justin D. R., Furtak, Lukas J., Oguri, Masamune, Zitrin, Adi, Diego, Jose M., Sharon, Keren, Coulter, David A., Brammer, Gabriel, Kokorev, Vasily, Nash, Chelsea, Abedi, Pedram, DeCoursey, Christa, Rest, Armin, Faisst, Andreas L., Frye, Brenda L., Hsiao, Tiger Yu-Yang, Inayoshi, Kohei, Kohno, Kotaro, Matthee, Jorryt, Messa, Matteo, Ono, Yoshiaki, Sun, Fengwu, Vanzella, Eros, Windhorst, Rogier A., Abdurro'uf, Agrawal, Aadya, Allingham, Joseph F. V., Asada, Yoshihisa, Atek, Hakim, Bradač, Maruša, Bradley, Larry D., Bronikowski, Mateusz, Coe, Dan, Conselice, Christopher J., Dayal, Pratika, Egami, Eiichi, Engesser, Michael, Farley, Gavin Scott, Fei, Qinyue, Fox, Ori D., Fudamoto, Yoshinobu, Golubchik, Miriam, Harikane, Yuichi, Khullar, Gourav, Kiyota, Tomokazu, Lopes, Paulo A. A., Lucas, Ray A., Mahler, Guillaume, Meena, Ashish Kumar, Naidu, Rohan P., Narayan, Gautham, Noirot, Gaël, Oesch, Pascal A., Ouchi, Masami, Palencia, José María, Pascale, Massimo, Robbins, Luke, Siebert, M. R., Tripodi, Roberta, Valentino, Francesco, Watson, Darach, Williams, Hayley, Yanagisawa, Hiroto, Zanella, Anita
Institutions: Space Telescope Science Institute, Ben-Gurion University of the Negev, Consejo Superior de Investigaciones Científicas, Instituto de Física de Cantabria, Johns Hopkins University, The University of Texas at Austin, University of Michigan, California Institute of Technology, Infrared Processing and Analysis Center, University of Arizona, Center for Astrophysics Harvard & Smithsonian, Arizona State University, Indiana University Bloomington, Indiana University, University of Illinois Urbana-Champaign, University of Toronto, Centre National de la Recherche Scientifique, Institut d'Astrophysique de Paris, Sorbonne Université, University of Warsaw, Chiba University, Center for Frontier Science, Chiba University, Institute for Cosmic Ray Research, The University of Tokyo, The Graduate University for Advanced Studies, SOKENDAI, National Astronomical Observatory of Japan, Universidade Federal do Rio de Janeiro, Valongo Observatory, University of Liège, Indian Institute of Science Bangalore, Massachusetts Institute of Technology, University of Geneva, University of Copenhagen, University of California, Los Angeles, Tufts University, Astronomical Observatory of Rome, National Institute for Astrophysics, DTU Space, Technical University of Denmark, Osservatorio di Astrofisica e Scienza dello Spazio
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1055883707, G6608474652, G6722835988, THE PROPOSAL SEEKS TO ACCOMPLISH SEVERAL INVESTIGATIONS TO SIMULATE THE PERFORMANCE OF JWST DEEP FIELD SURVEYS, VARYING AS-YET-POORLY CHARACTERIZED P, IN 2002 WE WERE GRANTED 110 HOURS GTO TIME FOR A JWST MEDIUM-DEEP SURVEY. WITH HST AND SPITZER EXPERIENCE 14 YEARS LATER WE REDEFINE THIS SURVEY TO IMAGE~18 NIRCAM FIELDS IN 7 FILTERS TO AB<~ 29 29.3 MAG YIELDING 140 000 GALAXIES AT 0<~ Z<~ 12 15 IN 0.05 DEG2 (>~ 30 HUDFS!). WE WILL STUDY GALAXY ASSEMBLY + SUPER-MASSIVE BLACK-HOLE GROWTH AT Z 0 7 INCLUDING OBJECT VARIABILITY ON MONTHS YEARS TIMESCALES. WE STUDY THE REIONIZING POPULATION AT Z 2 8 AND USE THE BEST LENSING TARGETS TO OPTIMIZE OUR STUDY OF FIRST LIGHT OBJECTS AT Z 10 15. OUR SCIENCE GOALS ARE: 1. GALAXY ASSEMBLY; 2. SUPER-MASSIVE BLACK-HOLE GROWTH; 3. REIONIZATION; 4. FIRST LIGHT; 5. STUDY THE BEST LENSING CLUSTERS TO FIND JWST OBJECTS. MAP&REMOVE STRAYLIGHT GRADIENTS AND QUANTIFY SAMPLE COMPLETENESS IN RANDOM FIELD&CLUSTER IMAGES: WE WILL: A) USE HUDF AND HFF DATA TO SIMULATE MAP AND REMOVE A RANGE OF STRAYLIGHT AMPLITUDES AND GRADIENTS THAT COULD AFFECT RANDOM DEEP FIELDS (DFS) AND CLUSTER FIELDS WITH JWST; B) DETERMINE ACCURATE COMPLETENESS CORRECTIONS VS. GALAXY FLUX SIZE WAVELENGTH AND LOCATION IN JWST DFS OF VARIOUS DEPTH AND IN CLUSTER FIELDS WITH THEIR KNOWN GALAXY CLUSTER+ICL FOREGROUND; C) DETERMINE THE CLUSTER SELECTION FUNCTIONS BY FOLDING LENSING MAPS WITH SIMULATED BACKGROUND IMAGES YIELDING SIMULATED LENSED IMAGES AND THEIR COMPLETENESS CORRECTIONS FOR LENSED SOURCES WHICH WE SHOW CAN BE FACTORS 2 3; AND D) MODEL COSMIC VARIANCE IN HIERARCHICAL MODELS AT Z 6 15. WE WILL CORRECT THE LFS FOR THESE COMPLETENESS FUNCTIONS. WE WILL THEN USE A BAYESIAN CODE TO DETERMINE THE OPTIMAL SET OF LF EVOLUTION PARAMETERS FROM THE AVAILABLE JWST DATA TO QUANTIFY HOW GALAXIES ASSEMBLED SINCE Z<~ 15., G8477266931
OpenAlex ID: W7214633936