A Consistent Modeling of Neutrino-driven Wind with Accretion Flow onto a Protoneutron Star and Its Implications for 56Ni Production

Details of the explosion mechanism of core-collapse supernovae (CCSNe) are not yet fully understood. There is now an increasing number of successful examples of reproducing explosions in the first-principles simulations, which have shown a slow increase of explosion energy. However, it was recently pointed out that the growth rates of the explosion energy of these simulations are insufficient to produce enough Ni-56 mass to account for observations. We refer to this issue as the nickel mass problem (Ni problem, hereafter) in this paper. The neutrino-driven wind is suggested as one of the most promising candidates for the solution to the Ni problem in previous literature, but a multidimensional simulation for this is computationally too expensive to allow long-term investigations. In this paper, we first built a consistent model of the neutrino-driven wind with an accretion flow onto a protoneutron star, by connecting a steady-state solution of the neutrino-driven wind and a phenomenological mass accretion model. Comparing the results of our model with the results of first-principles simulations, we find that the total ejectable amount of the neutrino-driven wind is roughly determined within similar to 1 s from the onset of the explosion and the supplementable amount at a late phase (t(e) greater than or similar to 1 s) remains M-ej less than or similar to 0.01 M at most. Our conclusion is that it is difficult to solve the Ni problem by continuous injection of Ni-56 by the neutrino-driven wind. We suggest that the total amount of synthesized Ni-56 can be estimated robustly if simulations are followed up to similar to 2 s.

Automated summary

This study investigates the mechanism of core-collapse supernovae explosions and the difficulty in explaining the observed Ni-56 mass, known as the Ni problem, through continuous injection by the neutrino-driven wind. The results suggest that estimating the total Ni-56 synthesized may be more robust by extending simulations up to around 2 seconds.