Measuring the Vortex−Nucleus Pinning Force from Pulsar Glitch Rates

Superfluid vortex avalanches are one plausible cause of pulsar glitch activity. If they occur according to a state-dependent Poisson process, the measured long-term rate is determined by spin-down stellar crust, $\dot{\Omega}_{\rm c}$, and two phenomenological parameters quantifying vortex-nucleus pinning force: crust-superfluid angular velocity lag threshold, $X_{\rm cr}$, reference unpinning rate, $\lambda_0$. A Bayesian analysis 541 glitches in 177 pulsars, with $N_{\rm g} \geq 1$ events per pulsar, yields cr} = 0.15^{+0.09}_{-0.04} \, {\rm rad s^{-1}}$, $\lambda_{\rm ref} 7.6^{+3.7}_{-2.6} \times 10^{-8} $a -0.27^{+0.04}_{-0.03}$ assuming law $\lambda_0 \lambda_{\rm [\tau/(1 yr})]^a$, where $\tau$ denotes characteristic age. The results broadly similar, whether includes or excludes quasiperiodic activity, giant glitches, pulsars g}=0$, up uncertainties about completeness sample total observation time pulsar. cr}$ $\lambda_0$ estimates consistent first-principles calculations based on nuclear theory, e.g. semiclassical local density approximation.