Vortex pinning and dynamics in the neutron star crust

TL;DR

This paper investigates how superfluid vortices interact with nuclei in neutron star crusts, revealing that nuclei repel vortices and influence their motion, which is key to understanding neutron star glitches.

Contribution

It introduces a new approach to model vortex-nucleus interactions, showing that nuclei repel vortices and characterizing the force as a function of separation.

Findings

Nuclei repel superfluid vortices in neutron star crusts.

Vortex motion is perpendicular to the applied force, similar to a spinning top.

The force between vortices and nuclei depends on their separation.

Abstract

The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force as a function of the vortex-nucleus separation.