On the distributions of pulsar glitch sizes and the inter-glitch time intervals

Abstract

The glitch size, Δν/ν, inter-glitch time interval, ti, and frequency of glitches in pulsars are key parameters in discussing glitch phenomena. In this paper, the glitch sizes and inter-glitch time intervals are statistically analyzed in a sample of 168 pulsars with a total of 483 glitches. The glitches are broadly divided into two groups. Those with Δν/ν < 10−7 are regarded as small size glitches, while those with Δν/ν ≥ 10−7 are considered as relatively large size glitches. In the ensemble of glitches, the distribution of Δν/ν is seen to be bimodal as usual. The distribution of inter-glitch time intervals is unimodal and the inter-glitch time intervals between small and large size glitches are not significantly different from each other. This observation shows that inter-glitch time intervals are size independent. In addition, the distribution of the ratio Δν/ν : ti in both small and large size glitches has the same pattern. This observation suggests that a parameter which depends on time, which could be the spin-down rate of a pulsar, plays a similar role in the processes that regulate both small and large size glitches. Equally, this could be an indication that a single physical mechanism, which could produce varying glitch sizes at similar time-intervals, could be responsible for both classes of glitch sizes.