On the Inner Crusts of Neo-Neutron Stars: exotic light nuclei, diffusional and thermodynamical stability

Abstract

Based on an extended nuclear statistical equilibrium model, we investigate the properties of non-accreted crusts of young and warm neo-neutron stars, i.e., of finite-temperature inhomogeneous dense matter in beta equilibrium. An interesting feature is the appearance, in the deep inner crust, of an extensive and almost pure layer of neutron-rich light nuclei that extends up to the density of the transition to homogeneous matter. Most probably, this layer emerges due to translational degrees of freedom of the nuclei. If confirmed, it will significantly impact the transport and elastic properties of the crust and its crystallization process. Then, we demonstrate that our inner crust is stable with respect to the diffusion of ions, which is in contrast with some of the predictions made in the literature for cold crusts. Finally, we show that clusterization completely exhausts the density instabilities that affect sub-saturated nuclear matter.