On the bimodal nature of the distributions of pulsar glitch sizes

TL;DR

This paper investigates the distribution of pulsar glitch sizes, revealing a bimodal pattern with small glitches following a lognormal distribution and large glitches following a normal distribution, suggesting different underlying mechanisms.

Contribution

It demonstrates that pulsar glitch sizes are bimodal, with distinct statistical distributions for small and large glitches, providing insights into their possible different origins.

Findings

Large glitches are normally distributed.

Small glitches follow a lognormal distribution.

Distribution patterns differ significantly between glitch sizes.

Abstract

Pulsar glitches are sudden spin-ups in pulsar spin frequency ($\nu$). The glitch size, $\Delta\nu/\nu$, is a key parameter in any mechanism puts across towards the understanding of the events.However, the distribution of the glitch sizes has persistently been bimodal.This bimodal nature could be intrinsic or otherwise. In this paper, the glitch size distribution is bisected at $\Delta\nu/\nu = 10^{-7}$ with $\Delta\nu/\nu < 10^{-7}$ being regarded as small size glitches (SSG), while those of $\Delta\nu/\nu > 10^{-7}$ are taken as large size glitches (LSG).The magnitude of SSGis scaled to that of LSG and tested for similarity.In pulsars with mixture of glitch sizes, Lilliefore test is used to identify the distribution pattern of SSGs and LSGs in such pulsars. The result indicates that each half of the size distribution is fundamentally different from one another. LSGs are seen to be normally distributed, while the SSGs are lognormal.