SIMBAD references

⁵⁶Ni is an important indicator of the supernova explosions, which characterizes light curves. Nevertheless, rather than ⁵⁶Ni, explosion energy has often been paid attention from explosion mechanism community, since it is, at a glance, easier to estimate from numerical data than the amount of ⁵⁶Ni. The final explosion energy, however, is difficult to estimate by detailed numerical simulations because current simulations cannot reach typical time-scale of saturation of the explosion energy. Instead, the amount of ⁵⁶Ni converges within a short time-scale so that it would be a more robust probe of the explosion mechanism. We investigated the amount of ⁵⁶Ni synthesized by explosive nucleosynthesis in supernova ejecta by means of numerical simulations and an analytic model. For numerical simulations, we employ a Lagrangian hydrodynamics code in which neutrino heating and cooling terms are taken into account by the light-bulb approximation. We additionally develop an analytic model, which gives a reasonable estimate of the amount of ⁵⁶Ni. We find that, in order to produce enough amount of ⁵⁶Ni, O(1) Bethe s^–1 of growth rate of the explosion energy is needed, which is much larger than those found in recent exploding simulations, typically O(0.1) Bethe s^–1. We also find that a progenitor model with a large compactness parameter leads to efficient synthesis of ⁵⁶Ni, opposite to the explodability that prefers a small compactness. These two results may indicate that there is a limited parameter space in the properties of the progenitor stars, which can explain both the explodability and ⁵⁶Ni production simultaneously.