Microscopic Vortex Velocity in the Inner Crust and Outer Core of Neutron Stars

TL;DR

This paper recalculates microscopic vortex velocities in neutron star crusts and cores, revealing significant differences that impact models of pulsar glitches and magnetic field evolution.

Contribution

It provides the first evaluation of vortex velocities in the outer core, highlighting the faster vortex motion in the crust and its implications for neutron star phenomena.

Findings

Vortex velocity in the crust is about 10^7 cm/s.

Vortex velocity in the outer core is about 1 cm/s.

Vortex creep is nonlinear in the outer core, but can be both in the crust.

Abstract

Treatment of the vortex motion in the superfluids of the inner crust and the outer core of neutron stars is a key ingredient in modeling a number of pulsar phenomena, including glitches and magnetic field evolution. After recalculating the microscopic vortex velocity in the inner crust, we evaluate the velocity for the vortices in the outer core for the first time. The vortex motion between pinning sites is found to be substantially faster in the inner crust than in the outer core, $v_0^{\rm crust} \sim 10^{7}\mbox{\cms} \gg v_0^{\rm core} \sim 1\mbox{\cms}$. One immediate result is that vortex creep is always in the nonlinear regime in the outer core in contrast to the inner crust, where both nonlinear and linear regimes of vortex creep are possible. Other implications for pulsar glitches and magnetic field evolution are also presented.