The broad-lined Type-Ic supernova SN 2022xxf and its extraordinary two-humped light curves

I. Signatures of H/He-free interaction in the first four months^★

¹ Tuorla Observatory, Department of Physics and Astronomy, 20014 University of Turku, Vesilinnantie 5, Turku, Finland
e-mail: kuncarayakti@gmail.com
² Finnish Centre for Astronomy with ESO (FINCA), 20014 University of Turku, Vesilinnantie 5, Turku, Finland
³ Department of Astronomy, Oskar Klein Centre, AlbaNova, Stockholm University, 106 91, Sweden
⁴ DARK, Niels Bohr Institute, University of Copenhagen, Niels Bohr Building (NBB), Jagtvej 155A, 1. floor, 2200 Copenhagen N., Denmark
⁵ Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
⁶ Henan Academy of Sciences, Zhengzhou 450046, Henan, PR China
⁷ Department of Physics, Oskar Klein Centre, AlbaNova, Stockholm University, 106 91, Sweden
⁸ Université Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France
⁹ School of Physics, The University of Melbourne, Parkville, VIC 3010, Australia
¹⁰ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Sydney 2006, Australia
¹¹ Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
¹² Capodimonte Astronomical Observatory, INAF-Napoli, Salita Moiariello 16, 80131 Napoli, Italy
¹³ Institut d’Astrophysique de Paris, CNRS-Sorbonne Université, 98 bis boulevard Arago, 75014 Paris, France
¹⁴ Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
¹⁵ Turku Collegium for Science, Medicine and Technology, University of Turku, 20014 Turku, Finland
¹⁶ Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
¹⁷ Department of Physics and Astronomy, University of California, 475 Portola Plaza, Los Angeles, CA 90095-1547, USA
¹⁸ Department of Physics & Astronomy, University of Southampton, Southampton SO17 1BJ, UK
¹⁹ Benoziyo Center for Astrophysics, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel
²⁰ Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, PR China
²¹ Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming 650216, PR China
²² School of Physics, O’Brien Centre for Science North, University College Dublin, Belfield, Dublin 4, Dublin, Ireland
²³ Department of Physics, Graduate School of Advanced Science and Engineering, Hiroshima University, Kagamiyama, 1-3-1 Higashi-Hiroshima, Hiroshima 739-8526, Japan
²⁴ European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago, Chile
²⁵ Nordic Optical Telescope, Aarhus Universitet, Rambla José Ana Fernández Pérez 7, local 5, E-38711 San Antonio, Breña Baja Santa Cruz de Tenerife, Spain
²⁶ School of Sciences, European University Cyprus, Diogenes street, Engomi, 1516 Nicosia, Cyprus
²⁷ INAF - Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122, Padova, Italy
²⁸ Università degli Studi di Padova, Dipartimento di Fisica e Astronomía, Vicolo dell’Osservatorio 2, 35122, Padova, Italy
²⁹ Millennium Institute of Astrophysics MAS, Nuncio Monsenor Sotero Sanz 100, Off. 104, Providencia, Santiago, Chile
³⁰ Department of Physics, Virginia Tech, 850 West Campus Drive, Blacksburg, VA 24061, USA
³¹ DIRAC Institute, Department of Astronomy, University of Washington, 3910 15th Avenue NE, Seattle, WA 98195, USA
³² Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
³³ Technische Universität München, TUM School of Natural Sciences, Physik-Department, James-Franck-Straße 1, 85748 Garching, Germany
³⁴ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Straße 1, 85748 Garching, Germany
³⁵ School of Physics and Astronomy, University of Minnesota, 116 Church St SE, Minneapolis, Minnesota 55455, USA
³⁶ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, 04510 D.F. Mexico, Mexico
³⁷ Division of Physics, Mathematics, and Astronomy, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
³⁸ The Caltech Optical Observatories, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
³⁹ Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Can Magrans, s/n, 08193 Barcelona, Spain
⁴⁰ Institut d’Estudis Espacials de Catalunya (IEEC), Gran Capità Street, 2-4, Nexus Building, office 201, 08034 Barcelona, Spain
⁴¹ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel
⁴² Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
⁴³ IPAC, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USA
⁴⁴ Cardiff Hub for Astrophysics Research and Technology, School of Physics & Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK
⁴⁵ Center for Data Driven Discovery, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
⁴⁶ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
⁴⁷ INAF - Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone (Roma), Italy
⁴⁸ Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
⁴⁹ Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Sayo, Hyogo 679-5313, Japan
⁵⁰ International Centre of Supernovae, Yunnan Key Laboratory, Kunming 650216, PR China
⁵¹ Space Science Data Center - ASI, Via del Politecnico snc, Edificio D, 00133 Roma, Italy

Received: 29 March 2023
Accepted: 7 August 2023

Abstract

We report on our study of the supernova (SN) 2022xxf based on observations obtained during the first four months of its evolution. The light curves (LCs) display two humps of similar maximum brightness separated by 75 days, unprecedented for a broad-lined (BL) Type Ic supernova (SN IcBL). SN 2022xxf is the most nearby SN IcBL to date (in NGC 3705, z = 0.0037, at a distance of about 20 Mpc). Optical and near-infrared photometry and spectroscopy were used to identify the energy source powering the LC. Nearly 50 epochs of high signal-to-noise ratio spectroscopy were obtained within 130 days, comprising an unparalleled dataset for a SN IcBL, and one of the best-sampled SN datasets to date. The global spectral appearance and evolution of SN 2022xxf points to typical SN Ic/IcBL, with broad features (up to ~14 000 km s⁻¹) and a gradual transition from the photospheric to the nebular phase. However, narrow emission lines (corresponding to ~ 1000–2500 km s⁻¹) are present in the spectra from the time of the second rise, suggesting slower-moving circumstellar material (CSM). These lines are subtle, in comparison to the typical strong narrow lines of CSM-interacting SNe, for example, Type IIn, Ibn, and Icn, but some are readily noticeable at late times, such as in Mg I λ5170 and [O I] λ5577. Unusually, the near-infrared spectra show narrow line peaks in a number of features formed by ions of O and Mg. We infer the presence of CSM that is free of H and He. We propose that the radiative energy from the ejecta-CSM interaction is a plausible explanation for the second LC hump. This interaction scenario is supported by the color evolution, which progresses to blue as the light curve evolves along the second hump, and by the slow second rise and subsequent rapid LC drop. SN 2022xxf may be related to an emerging number of CSM-interacting SNe Ic, which show slow, peculiar LCs, blue colors, and subtle CSM interaction lines. The progenitor stars of these SNe likely experienced an episode of mass loss consisting of H/He-free material shortly prior to explosion.