Time-dependent nuclear energy-density functional theory toolkit for neutron star crust: Dynamics of a nucleus in a neutron superfluid

TL;DR

This paper introduces a numerical toolkit based on time-dependent Hartree-Fock-Bogoliubov theory to study nuclear dynamics in neutron star crusts, revealing dissipation mechanisms and effective mass in superfluid neutron media.

Contribution

The paper develops a novel computational tool for simulating nuclear motion in neutron star crusts using advanced energy-density functionals, highlighting microscopic dissipation processes.

Findings

Identified threshold velocity for nuclear motion in superfluid medium.

Observed dissipation mechanisms: phonon emission, Cooper pair breaking, vortex ring creation.

Extracted effective mass of a nucleus in neutron superfluid.

Abstract

We present a new numerical tool designed to probe the dense layers of neutron star crusts. It is based on the time-dependent Hartree-Fock-Bogoliubov theory with generalized Skyrme nuclear energy-density functionals of the Brussels-Montreal family. We use it to study the time evolution of a nucleus accelerating through superfluid neutron medium in the inner crust of a neutron star. We extract an effective mass in the low velocity limit. We observe a threshold velocity and specify mechanisms of dissipation: phonon emission, Cooper pairs breaking, and vortex rings creation. These microscopic effects are of key importance for understanding various neutron star phenomena. Moreover, the mechanisms we describe are general and apply also to other fermionic superfluids interacting with obstacles like liquid helium or ultracold gases.