Statistical Study of Neutron Star Glitches

Abstract

Neutron star glitches; spanning a period of 42 years of pulsar timing were studied. These glitches are from Radio, X-ray, Anomalous X-ray and Milliseconds Pulsars. Radio Pulsars dominates the glitch events, contributing 87% of the glitches. Pulsars of characteristic age bracket 10 3 to 10 5 yrs dominated the glitch events, at a rate of 5.2 glitches per year per pulsar. Pulsar of the above age bracket exhibits large size glitches compared to others. A large frequency spin-up (△v) is generally associated with large frequency derivative jump (△). The distribution of the glitch magnitude (△v/v) is bimodal reaffirming dual glitch mechanism, but that of spin-up (△v) is tending towards multi-modal. Moreover, glitches in Vela pulsar and PSR J0537-6910 showed strong elasticity of the objects, suggesting that the interiors of these objects are in thermal equilibrium. Glitches from PSR J1740-3015 and PSR J1341-6220 appeared to occur in groups, suggesting that their interior fluid is switching between two phases. We discussed the glitch activity of young pulsars in terms of vortex creep model.

Statistical Study of Glitch Behaviours of Glitching Pulsars

“…There is a predominance of small glitches according to the authors for > 10 yr and <103 yr; and no large glitch has been reported for > 10 yr. This was corroborated by the report that large glitches are mostly exhibited by pulsars with characteristic age between 10 3 to 10 5 yr [12]. The glitch size distributions are consistent with power laws with the index varying from pulsar to pulsar [15].…”

“…It was shown that Vela pulsar, J0537-6910 and J1341-6220 show a quasiperiodic glitch pattern [15]. Vela alone was reported to have quasiregularly pattern [18], and a linear glitch pattern was also reported for Vela and J0537-6910 depicting also strong elasticity of the objects [12]. This corroborated the report that Vela and J0537-6910 have particular glitching behaviours or pattern and that such pattern may be shared by most Vela-like pulsars [11].…”

“…At the range of 3kyr to 100kyr, there appears to be a dominance of large glitches. Above 100kyr, we noticed a dominance of small glitches and pulsars with characteristic age greater than 10 7 yr had only small glitches in line with [12]. We also noticed some giant glitches among the very young pulsars with characteristic age, 1-3kyr.…”

“…Finally, glitch activity also seems to be dependent on age [7,11,12,19]. There also appears to be correlation between glitch activity and the spin down rate [11].…”

“…− ≤ ∆ν ν ≤ 10 [11], and with majority of the glitches having magnitude (∆ν /ν ) of between 10 -8 -10 -6 [12]. Glitches are grouped into two, namely: microglitches and macroglitches [13].…”