Knock-on processes in superfluid vortex avalanches and pulsar glitch statistics

Abstract

A framework is presented for a statistical theory of neutron star glitches, motivated by the results emerging from recent Gross-Pitaevskii simulations of pinned, decelerating quantum condensates. It is shown that the observed glitch size distributions cannot be reproduced if superfluid vortices unpin independently via a Poisson process; the central limit theorem yields a narrow Gaussian for the size distribution, instead of the broad, power-law tail observed. This conclusion is not altered fundamentally when a range of pinning potentials is included, which leads to excavation of the potential distribution of occupied sites, vortex accumulation at strong pinning sites, and hence the occasiona..