R-Process Nucleosynthesis in Neutron Star Merger Ejecta and Nuclear Dependences

Abstract

Despite the recent success of hydrodynamical simulations of binary compact objects, the details of r-processing in these events are still affected by a variety of uncertainties, including in particular those associated with the still complex nuclear physics description of exotic neutron-rich nuclei. R-process nucleosynthesis calculations require a reaction network consisting of about 5000 species from protons up to Z ≃ 110 lying between the valley of β-stability and the neutron drip line. Since only an extremely tiny amount of experimental data on neutron-rich nuclei produced during the r-process are known experimentally, theoretical models are crucial in providing the various predictions. Our capacity to predict fundamental nuclear ingredients, namely, nuclear masses, β-decay rates, radiative neutron capture rates, and fission probabilities, for all those 5000 nuclei is discussed in the present chapter. To analyze their impact on the r-process nucleosynthesis, a neutron star merger model including both the dynamical and wind ejecta and based on state-of-the-art hydrodynamical simulations is considered, and the model uncertainties are consistently propagated to illustrate their impact on the composition of the ejected material.