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

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 ${}^{13}N{(\alpha ,p)}^{16}O$, ${}^{17}F{(\alpha ,p)}^{20}Ne$, ${}^{52}Fe{(\alpha ,p)}^{55}Co$, ${}^{56}Ni{(\alpha ,p)}^{59}Cu$, ${}^{57}Ni{(n,p)}^{57}Co$, ${}^{56}Co{(p,n)}^{56}Ni$, ${}^{39}K{(p,\gamma )}^{40}Ca$, ${}^{47}V{(p,\gamma )}^{48}Cr$, ${}^{52}Mn{(p,\gamma )}^{53}Fe$, ${}^{57}Co{(p,\gamma )}^{58}Ni$, and ${}^{39}K{(p,\alpha )}^{36}Ar$ 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.