Hydrodynamical Effects on r-process Nucleosynthesis in Neutron Star Merger Accretion Disks

Computing r-process yields from astrophysical sites such as neutron star mergers and supernovae is a multi-step process. Since hydrodynamical simulations with in-situ nucleosynthesis are computationally expensive, post-processing nuclear reaction network codes, such as PRISM (Portable Routines for Integrated Nucleosynthesis Modeling), compute the isotopic evolution based on the thermodynamic quantities of temperature, density, and entropy extracted from these simulations. Contemporary reaction networks often account for thermal contributions from nuclear heating (from fission, beta-decay, etc), but such an approach computes the entropy from an equation of state and, thus, a different temperature progression than the inputted hydrodynamical data. While accounting for nuclear heating is crucial, other forms of heating, such as gaseous shocks, are ignored/imprecisely treated in current nucleosynthesis codes. A comprehensive treatment of a system's temperature evolution is necessary to accurately compute r-process abundances. We will report on our new version of PRISM, which not only accounts for nuclear heating effects but also restores the effects due to shock-heating by tracking the entropy from both nuclear heating and from shocks. We will highlight how this new version of PRISM alters the r-process peak abundances from NSMs relative to the standard nucleosynthesis approach by using tracers from nubhlight, a 3D general relativistic radiation magnetohydrodynamics (GRRMHD) neutron star merger accretion disk code with Monte Carlo-based neutrino transport.