Nuclear Uncertainties Associated with r-Process Nucleosynthesis

The rapid neutron capture process (r-process) is a complex nuclear physics phenomenon that is responsible for synthesizing about half the material heavier than iron in the universe, including the actinides . The astrophysical site of the r-process remains widely debated, but a largely supported location is in the outflows of neutron star mergers. Within the r-process, there are many nuclear uncertainties that make nucleosynthesis calculations difficult and predictions of postmerger isotopic compositions challenging to quantify. As β-decay is actively in competition with neutron capture and other dominant decay modes, variations in β-decay rates can greatly alter the distribution of isotopic material. Similarly, it is unknown whether existing nuclear mass models accurately describe the neutron-rich nuclei produced in postmerger outflows. In this project, we perform nucleosynthesis calculations for a set of tracers that describe a 3D simulated postmerger accretion disk while varying the theoretical nuclear mass model and β-decay rates. We investigate the impact these will have on the abundances produced at both 1 GYr and 3 minutes postmerger, which could greatly inform kilonova predictions as well as have implications for age predictions of metal-poor, r-process enhanced stars.