Letter to the Editor

Spectroscopy of the supernova H0pe host galaxy at redshift 1.78

¹ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, Via A. Corti 12, 20133 Milano, Italy
e-mail: maria.polletta@inaf.it
² INAF-Osservatorio Astronomico di Trieste, Via Bazzoni 2, 34124 Trieste, Italy
³ Steward Observatory, University of Arizona, 933 N Cherry Ave, Tucson, AZ 85721-0009, USA
⁴ Large Binocular Telescope Observatory, 933 North Cherry Ave, Tucson, AZ 85721, USA
⁵ Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, 69230 Saint-Genis-Laval, France
⁶ Department of Astronomy, University of California, 501 Campbell Hall #3411, Berkeley, CA 94720, USA
⁷ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
⁸ School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404, USA
⁹ Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS, Beijing 100101, PR China
¹⁰ CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, PR China
¹¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹² Association of Universities for Research in Astronomy (AURA) for the European Space Agency (ESA), STScI, Baltimore, MD 21218, USA
¹³ Center for Astrophysical Sciences, Department of Physics and Astronomy, The Johns Hopkins University, 3400 N Charles, St. Baltimore, MD 21218, USA
¹⁴ Jodrell Bank Centre for Astrophysics, Alan Turing Building, University of Manchester, Oxford Road, Manchester M13 9PL, UK
¹⁵ Department of Physics, University of California, 366 Physics North MC 7300, Berkeley, CA 94720, USA
¹⁶ FCA, Instituto de Fisica de Cantabria (UC-CSIC), Av. de Los Castros s/n, 39005 Santander, Spain
¹⁷ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
¹⁸ International Centre for Radio Astronomy Research (ICRAR) and the International Space Centre (ISC), The University of Western Australia, M468 35 Stirling Highway, Crawley
¹⁹ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australia
²⁰ INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monteporzio Catone, Rome, Italy
²¹ Physics Department, Ben-Gurion University of the Negev, PO Box 653 Be’er-Sheva 8410501, Israel
²² European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla, 19001 Santiago de Chile, Chile
²³ School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455, USA
²⁴ National Research Council of Canada, Herzberg Astronomy & Astrophysics Research Centre, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
²⁵ Minnesota State University-Mankato, Telescope Science Institute, TN141, Mankato, MN 56001, USA
²⁶ Max-Planck-Institut für extraterrestrische Physi, Garching 85741, Germany
²⁷ Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
²⁸ Department of Astronomy, University of Massachusetts at Amherst, Amherst, MA 01003, USA

Received: 22 May 2023
Accepted: 20 June 2023

Abstract

Supernova (SN) H0pe was discovered as a new transient in James Webb Space Telescope (JWST) NIRCam images of the galaxy cluster PLCK G165.7+67.0 taken as part of the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) JWST GTO program (ID 1176) on 2023 March 30. The transient is a compact source associated with a background galaxy that is stretched and triply imaged by the strong gravitational lensing of the cluster. This paper reports spectra in the 950–1370 nm observer frame of two of the galaxy images obtained with Large Binocular Telescope (LBT) Utility Camera in the Infrared (LUCI) in long-slit mode two weeks after the JWST observations. The individual and average spectra show the [O II] λλ3727,3730 doublet and the Balmer and 4000 Å breaks at redshift z = 1.783 ± 0.002. The code investigating galaxy emission (CIGALE) best-fit model of the spectral energy distribution indicates that the host galaxy of SN H0pe is massive (M_star ≃ 6 × 10¹⁰ M_⊙ after correcting for a magnification factor μ ∼ 7) with a predominantly intermediate-age (∼2 Gyr) stellar population, moderate extinction, and a magnification-corrected star formation rate ≃13 M_⊙ yr⁻¹, consistent with being below the main sequence of star formation. These properties suggest that H0pe might be a type Ia SN. Additional observations of SN H0pe and its host recently carried out with JWST (JWST-DD-4446; PI: B. Frye) will be able to both determine the SN classification and confirm its association with the galaxy analyzed in this work.