Follow-up phot. & sp. of SNIa 2020hvf

The fast evolution of the early flash was captured by intensive intranight observations via the Tomo-e Gozen high-cadence survey. Numerical simulations show that such a prominent and fast early emission is most likely generated from an interaction between 0.01M_{sun}_ circumstellar material (CSM) extending to a distance of ~10^13^cm and supernova ejecta soon after the explosion, indicating a confined dense CSM formation at the final evolution stage of the progenitor of SN 2020hvf.

Based on the CSM-ejecta interaction-induced early flash, the overluminous light curve, and the high ejecta velocity of SN 2020hvf, we suggest that the SN 2020hvf may originate from a thermonuclear explosion of a super-Chandrasekhar-mass white dwarf ("super-M_Ch_ WD"). Systematical investigations on explosion mechanisms and hydrodynamic simulations of the super-M_Ch_ WD explosion are required to further test the suggested scenario and understand the progenitor of this peculiar supernova.