Coulomb forces in neutron star crusts

TL;DR

This study investigates how proton-electron Coulomb interactions influence nuclear structure formation in neutron star crusts, revealing effects on matter distribution, cluster properties, and structural shapes through molecular dynamics simulations.

Contribution

It introduces a detailed analysis of Coulomb interaction effects on nuclear structures in neutron star crusts using classical molecular dynamics, highlighting new insights into matter distribution and cluster properties.

Findings

Coulomb interaction distributes matter more evenly

Disrupts formation of larger nuclear objects

Reduces isospin content in clusters

Abstract

We study the role the proton-electron gas interaction has on the formation of nuclear structures in neutron star crusts. Using a classical molecular dynamics model we study isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength. The effect of such variation is quantified on the fragment size multiplicity, the inter-particle distance, the isospin content of the clusters, the nucleon mobility and cluster persistence, and on the nuclear structure shapes. We find that the proton-electron Coulomb interaction distributes matter more evenly, disrupts the formation of larger objects, reduces the isospin content, modifies the nucleon average displacement, but does not affect the inter-nucleon distance in clusters . The nuclear structures are also found to change shapes by different degrees depending on their isospin content, temperature and density.