# Fission and the r-process nucleosynthesis of translead nuclei in neutron star mergers

## TL;DR

This paper investigates how fission influences the formation and destruction of translead nuclei during the r-process in neutron-star mergers, affecting kilonova emissions and heavy element abundances.

## Contribution

It introduces detailed modeling of fission effects on r-process nucleosynthesis using various nuclear reaction rate sets, including microscopic calculations.

## Key findings

- Fission significantly alters heavy element abundance patterns.
- Fission impacts free neutron availability after r-process freeze-out.
- Radioactive energy production is affected by fission during kilonova timescales.

## Abstract

We study the impact of fission on the production and destruction of translead nuclei during the r-process nucleosynthesis occurring in neutron-star mergers. Abundance patterns and rates of nuclear energy production are obtained for different ejecta conditions using three sets of stellar reaction rates, one of which is based on microscopic and consistent calculations of nuclear masses, fission barriers, and collective inertias. We show that the accumulation of fissioning material during the r process can strongly affect the free neutron abundance after the r-process freeze-out. This leads to a significant impact on the abundances of heavy nuclei that undergo $\alpha$ decay or spontaneous fission, affecting the radioactive energy production by the ejecta at timescales relevant for kilonova emission.