Sensitivity ofr‐Process Nucleosynthesis to Light‐Element Nuclear Reactions

We study the efficiency and sensitivity of r-process nucleosynthesis to 18light-element nuclear reaction rates. We adopt empirical power-law relations toparameterize the reaction sensitivities. We utilize two different hydrodynamicmodels for the neutrino-driven winds in order to study the dependence of ourresult on supernova wind models. We also utilize an exponential model toapproximate a wide variety of other plausible conditions for the r-process. Weidentify several specific nuclear reactions among light neutron-rich nucleithat play a critical role in determining the final r-process nucleosynthesisyields. As an illustration, we examine ``semi-waiting'' points among the carbonisotopes. We show that not only neutron capture and $\beta$-decay, but also $(\alpha, \mathrm{n})$ reactions are important indetermining waiting points along the r-process path. Our numerical results fromthis sensitivity analysis serve foremost to clarify which light nuclearreactions are most influential in determining the final r-process abundances.We also quantify the effects of present nuclear uncertainties on the finalr-process abundances. This study thus emphasizes and motivates which futuredeterminations of nuclear reaction rates will most strongly impact ourunderstanding of r-process nucleosynthesis.Comment: ApJ (2005) in press, 47pages, 13figure