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

March 2022 • 2022ApJ...927..180P

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

Abstract • 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.

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Frank Masci

Senior Scientist

Dave Shupe

Senior Scientist