Sensitivity of ⁴⁴Ti and ⁵⁶Ni Production in Core-collapse Supernova Shock-driven Nucleosynthesis to Nuclear Reaction Rate Variations

Abstract

Recent observational advances have enabled high resolution mapping of 44Ti in core-collapse supernova (CCSN) remnants. Comparisons between observations and models provide stringent constraints on the CCSN mechanism. However, past work has identified several uncertain nuclear reaction rates that influence 44Ti and 56Ni production in postprocessing model calculations. We evolved one-dimensional models of 15 M ⊙, 18 M ⊙, 22 M ⊙, and 25 M ⊙ stars from zero age main sequence through CCSN using Modules for Experiments in Stellar Astrophysics and investigated the previously identified reaction rate sensitivities of 44Ti and 56Ni production. We tested the robustness of our results by making various assumptions about the CCSN explosion energy and mass cut. We found a number of reactions that have a significant impact on the nucleosynthesis of 44Ti and 56Ni, particularly for lower progenitor masses. Notably, the reaction rates , , , , , , , , , , and are influential for a large number of model conditions. Furthermore, we found the list of influential reactions identified by previous postprocessing studies of CCSN shock-driven nucleosynthesis is likely incomplete, motivating future larger-scale sensitivity studies.

Experiments probing clustering effects in explosive nucleosynthesis

“…The 44 Ti(α, p) 47 V, 40 Ca(α, γ) 44 Ti, 40 Ca(α, p) 43 Sc, 17 F(α, p) 20 Ne, and 21 Na(α, p) 24 Mg reactions were identified by Magkotsios et al [10] as affecting 44 Ti and 56 Ni production. On the other hand, Subedi, Meisel, and Merz [55] identified 13 N(α, p) 16 O, 17 F(α, p) 20 Ne, 52 Fe(α, p) 55 Co, 56 Ni(α, p) 59 Cu, and 39 K(p, α) 36 Ar as some of the most important α-cluster reactions. While studies do not always agree on the most important reactions to constrain, it is clear that α-clusterized nuclei are important for nucleosynthesis in CCSN.…”

Estimation of the NiCu Cycle Strength and Its Impact on Type I X-Ray Bursts

“…Recent sensitivity studies of core-collapse supernovae (CCSNe) to nuclear reaction rates showed that the 59 Cu(p,α) 56 Ni and 59 Cu(p,γ) 60 Zn reaction rate variations notably affect the production of γ-ray emitting isotopes (Hermansen et al 2020;Subedi et al 2020). As CCSNe also accompany the rp process, the NiCu cycle or individual reactions can affect the CCSNe model predictions.…”

First direct measurement of the $^{13}$N($α$,$p$)$^{16}$O reaction relevant for core-collapse supernovae nucleosynthesis

“…A large number of nuclear reactions affect the production of these isotopes and precise knowledge of nuclear reaction rates are needed to constrain astrophysical models and to obtain accurate information about the CCSN. A recent sensitivity study was performed by Subedi et al [1], in which the rates of various reactions were varied and their impact on the synthesis of 44 Ti and 56 Ni isotopes were inferred. In these calculations, a 1-D model was evolved for 15 ∼ M , 18 ∼ M and 22 ∼ M progenitor stars from zero-age main sequence through the explosion.…”