Dynamics of the inner crust of neutron stars: hydrodynamics, elasticity and collective modes

TL;DR

This paper models the hydrodynamics and collective oscillations in the inner crust of neutron stars, focusing on superfluid neutrons and nuclear lattice interactions, providing insights into their dynamic behavior.

Contribution

It introduces a detailed calculation of collective modes combining superfluid and lattice phonons using effective nucleon interactions derived from microscopic models.

Findings

Velocities of collective modes are quantified.

Superfluid and lattice phonons are coupled in the crust dynamics.

Results inform neutron star oscillation models.

Abstract

We present calculations of the hydrodynamics of the inner crust of neutron stars, where a superfluid neutron liquid coexists with a lattice of neutron-rich nuclei. The long-wavelength collective oscillations are combinations of phonons in the lattice and phonons in the superfluid neutrons. Velocities of collective modes are calculated from information about effective nucleon-nucleon interactions derived from Lattimer and Swesty's microscopic calculations based on a compressible liquid drop picture of the atomic nuclei and the surrounding neutrons.