Size-waiting-time correlations in pulsar glitches

TL;DR

This paper investigates the correlations between pulsar glitch sizes and waiting times, revealing that threshold-triggered models combined with stellar braking explain the observed lack of correlations, and predicts future observable correlations.

Contribution

It introduces a model combining threshold-triggered glitches with stellar braking to explain the absence of size-waiting-time correlations in pulsars.

Findings

Lack of correlation explained by threshold-triggered glitches with slow stellar braking

Strong correlation observed in PSR J0537-6910 is consistent with the model

Predictions made for future observations to test the model

Abstract

Few statistically compelling correlations are found in pulsar timing data between the size of a rotational glitch and the time to the preceding glitch (backward waiting time) or the succeeding glitch (forward waiting time), except for a strong correlation between sizes and forward waiting times in PSR J0537-6910. This situation is counterintuitive, if glitches are threshold-triggered events, as in standard theories (e.g. starquakes, superfluid vortex avalanches). Here it is shown that the lack of correlation emerges naturally, when a threshold trigger is combined with secular stellar braking slower than a critical, calculable rate. The Pearson and Spearman correlation coefficients are computed and interpreted within the framework of a state-dependent Poisson process. Specific, falsifiable predictions are made regarding what objects currently targeted by long-term timing campaigns should develop strong size-waiting-time correlations, as more data are collected in the future.