Work

Temperature-resolved sensitivities of 56Ni production to helium-burning reactions in pair-instability supernovae

Year: 2026

Type: article

Abstract: We propose a temperature-resolved Monte Carlo (MC) approach to identify the temperature ranges in which low-energy helium-burning reaction rates most strongly affect nucleosynthesis in very massive stars that undergo pair-instability supernovae (PISNe). By performing MC simulations of PISNe, we quantify how temperature-dependent variations in key helium-burning reaction rates, i.e., the triple-α and ${}^{12}{\rm C}(\alpha ,\gamma ){}^{16}{\rm O}$ rates, influence $^{56}\mathrm{Ni}$ synthesis. Thousands of stellar evolution calculations using MESA reveal that both the ${}^{12}{\rm C}(\alpha ,\gamma ){}^{16}{\rm O}$ and triple-α reactions exhibit their strongest sensitivity at $T \simeq 2.5 \times 10^{8}\, \mathrm{K}$, but with opposite correlation signs. We show that this temperature corresponds to the regime in which the ratio of the sampled rate multipliers is most clearly imprinted on the pre-carbon-burning C/O composition. This demonstrates that PISN nucleosynthesis can probe helium-burning reaction rates in specific low-temperature regimes.

Source: Publications of the Astronomical Society of Japan

DOI: 10.1093/pasj/psag137

Authors: Hiroki Kawashimo, Nobuya Nishimura, Yudai Suwa