Superfluid turbulence and pulsar glitch statistics

TL;DR

This paper reviews evidence for superfluid turbulence in neutron star cores and suggests a link between turbulence-related dynamics and pulsar glitch activity, supported by statistical analysis of glitch data.

Contribution

It introduces a connection between superfluid turbulence in neutron stars and pulsar glitch statistics, supported by experimental and statistical evidence.

Findings

Torque variability increases with Reynolds number.

Different Reynolds number distributions for glitching and non-glitching pulsars.

The difference in distributions is statistically significant.

Abstract

Experimental evidence is reviewed for the existence of superfluid turbulence in a differentially rotating, spherical shell at high Reynolds numbers ($\Rey\gsim 10^3$), such as the outer core of a neutron star. It is shown that torque variability increases with $\Rey$, suggesting that glitch activity in radio pulsars may be a function of $\Rey$ as well. The $\Rey$ distribution of the 67 glitching radio pulsars with characteristic ages $\tau_c \leq 10^6$ {\rm yr} is constructed from radio timing data and cooling curves and compared with the $\Rey$ distribution of all 348 known pulsars with $\tau_c \leq 10^6$ {\rm yr}. The two distributions are different, with a Kolmogorov-Smirnov probability $\geq 1 - 3.9 \times 10^{-3}$. The conclusion holds for (modified) Urca and nonstandard cooling, and for Newtonian and superfluid viscosities.