Type Ic SN 2020bvc UV to NIR LCs and opt. spectra

Third, high-cadence (6x 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 M_e_<10^-2^M_{sun}_ at radius R_e_>10^12^cm) and the second peak from the radioactive decay of ^56^Ni. 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 ~1day 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.