SN 2020bvc: A Broad-line Type Ic Supernova with a Double-peaked Optical Light Curve and a Luminous X-Ray and Radio Counterpart

Anna Y.Q. Ho, S. R. Kulkarni, Daniel A. Perley, S. Bradley Cenko, Alessandra Corsi, Steve Schulze, Ragnhild Lunnan, Jesper Sollerman, Avishay Gal-Yam, Shreya Anand, Cristina Barbarino, Eric C. Bellm, Rachel J. Bruch, Eric Burns, Kishalay De, Richard Dekany, Alexandre Delacroix, Dmitry A. Duev, Dmitry D. Frederiks, Christoffer FremlingDaniel A. Goldstein, V. Zach Golkhou, Matthew J. Graham, David Hale, Mansi M. Kasliwal, Thomas Kupfer, Russ R. Laher, Julia Martikainen, Frank J. Masci, James D. Neill, Anna Ridnaia, Ben Rusholme, Volodymyr Savchenko, David L. Shupe, Maayane T. Soumagnac, Nora L. Strotjohann, Dmitry S. Svinkin, Kirsty Taggart, Leonardo Tartaglia, Lin Yan, Jeffry Zolkower

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We present optical, radio, and X-ray observations of SN 2020bvc (=ASASSN-20bs, ZTF 20aalxlis), a nearby broad-line (BL) Type Ic supernova (SN) and the first double-peaked Ic-BL discovered without a gamma-ray burst (GRB) trigger. Our observations show that SN 2020bvc shares several properties in common with the Ic-BL SN 2006aj, which was associated with the low-luminosity gamma-ray burst (LLGRB) 060218. First, the 10 GHz radio luminosity is brighter than ordinary core-collapse SNe but fainter than LLGRB SNe such as SN 1998bw (associated with LLGRB 980425). We model our VLA observations (spanning 13-43 days) as synchrotron emission from a mildly relativistic (v 0.3c) forward shock. Second, with Swift and Chandra, we detect X-ray emission (L X 1041 erg that is not naturally explained as inverse Compton emission or part of the same synchrotron spectrum as the radio emission. Third, high-cadence (6× night-1) data from the Zwicky Transient Facility (ZTF) show a double-peaked optical light curve, the first peak from shock cooling of extended low-mass material (mass SN 2020bvc is the first double-peaked Ic-BL SN discovered without a GRB trigger, so it is noteworthy that it shows X-ray and radio emission similar to LLGRB SNe. For four of the five other nearby (z ≲ 0.05) Ic-BL SNe with ZTF high-cadence data, we rule out a first peak like that seen in SN 2006aj and SN 2020bvc, i.e., that lasts 1 day and reaches a peak luminosity M -18. Follow-up X-ray and radio observations of Ic-BL SNe with well-sampled early optical light curves will establish whether double-peaked optical light curves are indeed predictive of LLGRB-like X-ray and radio emission.

Original languageEnglish
Article number86
JournalAstrophysical Journal
Issue number1
StatePublished - 10 Oct 2020
Externally publishedYes

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