Constraints on the Explosion Timescale of Core-collapse Supernovae Based on Systematic Analysis of Light Curves

The explosion mechanism of core-collapse supernovae is not fully understood yet. In this work, we give constraints on the explosion timescale based on ⁵⁶Ni synthesized by supernova explosions. First, we systematically analyze multiband light curves of 82 stripped-envelope supernovae (SESNe) to obtain bolometric light curves, which is among the largest samples of the bolometric light curves of SESNe derived from the multiband spectral energy distribution. We measure the decline timescale and the peak luminosity of the light curves and estimate the ejecta mass (M _ej) and ⁵⁶Ni mass (M _Ni) to connect the observed properties with the explosion physics. We then carry out one-dimensional hydrodynamics and nucleosynthesis calculations, varying the progenitor mass and the explosion timescale. From the calculations, we show that the maximum ⁵⁶Ni mass that ⁵⁶Ni-powered SNe can reach is expressed as M _Ni ≲ 0.2 M _ej. Comparing the results from the observations and the calculations, we show that the explosion timescale shorter than 0.3 s explains the synthesized ⁵⁶Ni mass of the majority of the SESNe.