The Type Icn SN 2021csp: Implications for the Origins of the Fastest Supernovae and the Fates of Wolf-Rayet Stars

Daniel A. Perley, Jesper Sollerman, Steve Schulze, Yuhan Yao, Christoffer Fremling, Avishay Gal-Yam, Anna Y.Q. Ho, Yi Yang, Erik C. Kool, Ido Irani, Lin Yan, Igor Andreoni, Dietrich Baade, Eric C. Bellm, Thomas G. Brink, Ting Wan Chen, Aleksandar Cikota, Michael W. Coughlin, Aishwarya Dahiwale, Richard DekanyDmitry A. Duev, Alexei V. Filippenko, Peter Hoeflich, Mansi M. Kasliwal, S. R. Kulkarni, Ragnhild Lunnan, Frank J. Masci, Justyn R. Maund, Michael S. Medford, Reed Riddle, Philippe Rosnet, David L. Shupe, Nora Linn Strotjohann, Anastasios Tzanidakis, Weikang Zheng

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We present observations of SN 2021csp, the second example of a newly identified type of supernova (SN) hallmarked by strong, narrow, P Cygni carbon features at early times (Type Icn). The SN appears as a fast and luminous blue transient at early times, reaching a peak absolute magnitude of -20 within 3 days due to strong interaction between fast SN ejecta (v ≈ 30,000 km s-1) and a massive, dense, fast-moving C/O wind shed by the WC-like progenitor months before explosion. The narrow-line features disappear from the spectrum 10-20 days after explosion and are replaced by a blue continuum dominated by broad Fe features, reminiscent of Type Ibn and IIn supernovae and indicative of weaker interaction with more extended H/He-poor material. The transient then abruptly fades ∼60 days post-explosion when interaction ceases. Deep limits at later phases suggest minimal heavy-element nucleosynthesis, a low ejecta mass, or both, and imply an origin distinct from that of classical Type Ic SNe. We place SN 2021csp in context with other fast-evolving interacting transients, and discuss various progenitor scenarios: an ultrastripped progenitor star, a pulsational pair-instability eruption, or a jet-driven fallback SN from a Wolf-Rayet (W-R) star. The fallback scenario would naturally explain the similarity between these events and radio-loud fast transients, and suggests a picture in which most stars massive enough to undergo a W-R phase collapse directly to black holes at the end of their lives.

Original languageEnglish (US)
Article number180
JournalAstrophysical Journal
Issue number2
StatePublished - Mar 1 2022

Bibliographical note

Funding Information:
J.S., S.S., and E.K. acknowledge support from the G.R.E.A.T. research environment funded by Vetenskapsrådet, the Swedish Research Council, under project #2016-06012. The OKC’s participation in ZTF was made possible by the K.A.W. foundation. E.K. also acknowledges support from The Wenner-Gren Foundation. M.M.K. acknowledges generous support from the David and Lucille Packard Foundation. P.R. has received support from the from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement 759194—USNAC). The research of Y.Y. is supported through a Benoziyo Prize Postdoctoral Fellowship and a Bengier-Winslow-Robertson Fellowship. T.-W.C. acknowledges EU funding under Marie Skłodowska-Curie grant H2020-MSCA-IF-2018-842471. R.L. acknowledges support from a Marie Skłodowska-Curie Individual Fellowship within the Horizon 2020 European Union (EU) Framework Programme for Research and Innovation (H2020-MSCA-IF-2017-794467). The GROWTH Marshal (Kasliwal et al. ) development was supported by the GROWTH project funded by the NSF under grant 1545949. A.V.F.'s group is supported by the Christopher R. Redlich Fund, the Miller Institute for Basic Research in Science (where A.V.F. is a Miller Senior Fellow), and many individual donors. A.G.Y.s research is supported by the EU via ERC grant No. 725161, the ISF GW excellence center, an IMOS space infrastructure grant and BSF/Transformative and GIF grants, as well as The Benoziyo Endowment Fund for the Advancement of Science, the Deloro Institute for Advanced Research in Space and Optics, The Veronika A. Rabl Physics Discretionary Fund, Minerva, Yeda-Sela and the Schwartz/Reisman Collaborative Science Program; A.G.Y. is the incumbent of the The Arlyn Imberman Professorial Chair.

Funding Information:
IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the NSF.

Funding Information:
We thank Ori Fox, D. Alexander Kann, and the anonymous referee for helpful comments and suggestions. Based on observations obtained with the Samuel Oschin 48 inch telescope 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 (NSF) under grant AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center (OKC) 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, and IN2P3, France. Operations are conducted by COO, IPAC, and UW. The SED Machine is based upon work supported by the NSF under grant 1106171. The ZTF forced-photometry service was funded by Heising-Simons Foundation grant No. 12540303 (PI: M. Graham). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Partly 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 (respectively 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. These data were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT. Based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 106.21U2 and 106.216C. 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 NASA; the observatory was made possible by the generous financial support of the W. M. Keck Foundation. A major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory was made possible through generous gifts from the Heising-Simons Foundation as well as William and Marina Kast. Research at Lick Observatory is partially supported by a generous gift from Google. We thank the staffs of the various observatories where data were obtained for their assistance.

Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.


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