Quantification of nuclear uncertainties in nucleosynthesis of elements beyond Iron

TL;DR

This paper discusses the challenges in quantifying nuclear uncertainties in nucleosynthesis beyond Iron, emphasizing sensitivity analysis, theoretical contributions, and improved uncertainty estimation methods, with applications to W isotopes and the s-process.

Contribution

It introduces an improved uncertainty analysis framework and sensitivity studies for stellar reaction rates, enhancing the interpretation of experimental data and theoretical predictions for nucleosynthesis beyond Iron.

Findings

Large-scale sensitivity predictions for reactions like 185W(n,gamma) and 186W(gamma,n).

Enhanced uncertainty estimates for neutron capture rates in the s-process.

Demonstrated larger uncertainties in abundance predictions than previously assumed.

Abstract

Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Generally higher temperatures and nuclear level densities lead to stronger contributions of transitions on excited target states. This may prevent cross section measurements to determine stellar reaction rates and theory contributions remain important. Furthermore, measurements often are not feasible in the astrophysically relevant energy range. Sensitivity analysis allows not only to determine the contributing nuclear properties but also is a handy tool for experimentalists to interpret the impact of their data on predicted cross sections and rates. It can also speed up future input variation studies of nucleosynthesis by simplifying an intermediate step in the full calculation sequence. Large-scale predictions of sensitivities and ground-state contributions to the stellar rates are presented, allowing an estimate of how well rates can be directly constrained by experiment. The reactions 185W(n,gamma) and 186W(gamma,n) are discussed as application examples. Studies of uncertainties in abundances predicted in nucleosynthesis simulations rely on the knowledge of reaction rate errors. An improved treatment of uncertainty analysis is presented as well as a recipe for combining experimental data and theory to arrive at a new reaction rate and its uncertainty. As an example, it is applied to neutron capture rates for the s-process, leading to larger uncertainties than previously assumed.