Supernova 2020wnt: An Atypical Superluminous Supernova with a Hidden Central Engine

Samaporn Tinyanont*, Stan E. Woosley, Kirsty Taggart, Ryan J. Foley, Lin Yan, Ragnhild Lunnan, Kyle W. Davis, Charles D. Kilpatrick, Matthew R. Siebert, Steve Schulze, Chris Ashall, Ting Wan Chen, Kishalay De, Georgios Dimitriadis, Dillon Z. Dong, Christoffer Fremling, Alexander Gagliano, Saurabh W. Jha, David O. Jones, Mansi M. KasliwalHao Yu Miao, Yen Chen Pan, Daniel A. Perley, Vikram Ravi, César Rojas-Bravo, Itai Sfaradi, Jesper Sollerman, Vanessa Alarcon, Rodrigo Angulo, Karoli E. Clever, Payton Crawford, Cirilla Couch, Srujan Dandu, Atirath Dhara, Jessica Johnson, Zhisen Lai, Carli Smith

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

We present observations of a peculiar hydrogen- and helium-poor stripped-envelope (SE) supernova (SN) 2020wnt, primarily in the optical and near-infrared (near-IR). Its peak absolute bolometric magnitude of −20.9 mag (L bol, peak = (6.8 ± 0.3) × 1043 erg s−1) and a rise time of 69 days are reminiscent of hydrogen-poor superluminous SNe (SLSNe I), luminous transients potentially powered by spinning-down magnetars. Before the main peak, there is a brief peak lasting <10 days post explosion, likely caused by interaction with circumstellar medium (CSM) ejected ∼years before the SN explosion. The optical spectra near peak lack a hot continuum and O ii absorptions, which are signs of heating from a central engine; they quantitatively resemble those of radioactivity-powered hydrogen/helium-poor Type Ic SESNe. At ∼1 yr after peak, nebular spectra reveal a blue pseudo-continuum and narrow O i recombination lines associated with magnetar heating. Radio observations rule out strong CSM interactions as the dominant energy source at +266 days post peak. Near-IR observations at +200-300 days reveal carbon monoxide and dust formation, which causes a dramatic optical light-curve dip. Pair-instability explosion models predict slow light curve and spectral features incompatible with observations. SN 2020wnt is best explained as a magnetar-powered core-collapse explosion of a 28 M pre-SN star. The explosion kinetic energy is significantly larger than the magnetar energy at peak, effectively concealing the magnetar-heated inner ejecta until well after peak. SN 2020wnt falls into a continuum between normal SNe Ic and SLSNe I, and demonstrates that optical spectra at peak alone cannot rule out the presence of a central engine.

Original languageEnglish (US)
Article number34
JournalAstrophysical Journal
Volume951
Issue number1
DOIs
StatePublished - Jul 1 2023

Funding

We thank Norbert Langer, Matt Nicholl, Conor Omand, Dan Kasen, David Khatami, Anders Jerkstrand, and Heloise Stevance for helpful discussions. We also thank the organizers of the IAU360 Massive Stars Near and Far symposium, where a lot of helpful discussions about this object were made. We thank Robert Quimby for providing data points used to make Figure 6. We thank Matt Nicholl for providing the mean SLSN and SN Ic spectra for Figure 7. S.S. acknowledges support from the G.R.E.A.T research environment, funded by Vetenskapsrådet, the Swedish Research Council, under project number 2016-06012. A.G. acknowledges support from the Flatiron Institute Center for Computational Astrophysics Pre-Doctoral Fellowship Program in Spring 2022. A.G. is also supported by the Illinois Distinguished Fellowship, the National Science Foundation Graduate Research Fellowship Program under grant No. DGE1746047, and the Center for Astrophysical Surveys Graduate Fellowship at the University of Illinois. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. NIRES data presented in this paper were supported in part by NASA Keck PI Data Awards 2020B_N141 and 2021A_N147 (PI: Jha), administered by the NASA Exoplanet Science Institute. Parts of this work are based on observations obtained at the international Gemini Observatory, a program of the NSF’s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This work uses data from the Infrared Telescope Facility, which is operated by the University of Hawaii under contract 80HQTR19D0030 with the National Aeronautics and Space Administration. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Parts of this work are based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant Nos. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant No. 12540303 (PI: Graham). Parts of this work are based on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland, and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. We thank Norbert Langer, Matt Nicholl, Conor Omand, Dan Kasen, David Khatami, Anders Jerkstrand, and Heloise Stevance for helpful discussions. We also thank the organizers of the IAU360 Massive Stars Near and Far symposium, where a lot of helpful discussions about this object were made. We thank Robert Quimby for providing data points used to make Figure . We thank Matt Nicholl for providing the mean SLSN and SN Ic spectra for Figure . S.S. acknowledges support from the G.R.E.A.T research environment, funded by Vetenskapsrådet, the Swedish Research Council, under project number 2016-06012. A.G. acknowledges support from the Flatiron Institute Center for Computational Astrophysics Pre-Doctoral Fellowship Program in Spring 2022. A.G. is also supported by the Illinois Distinguished Fellowship, the National Science Foundation Graduate Research Fellowship Program under grant No. DGE1746047, and the Center for Astrophysical Surveys Graduate Fellowship at the University of Illinois. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. NIRES data presented in this paper were supported in part by NASA Keck PI Data Awards 2020B_N141 and 2021A_N147 (PI: Jha), administered by the NASA Exoplanet Science Institute. Parts of this work are based on observations obtained at the international Gemini Observatory, a program of the NSF’s NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). This work uses data from the Infrared Telescope Facility, which is operated by the University of Hawaii under contract 80HQTR19D0030 with the National Aeronautics and Space Administration. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Parts of this work are based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant Nos. AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant No. 12540303 (PI: Graham). Parts of this work are based on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland, and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias.

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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