Glitch analysis and braking index determination of the unique source PSR J0537-6910

TL;DR

This study reanalyzed 45 glitches of PSR J0537-6910, modeling its glitch behavior with vortex creep theory, estimating internal temperature, and refining its braking index, revealing insights into its superfluid dynamics and long-term rotational evolution.

Contribution

The paper provides a detailed vortex creep model analysis of PSR J0537-6910's glitches, estimating internal temperature and updating its braking index, offering new insights into young pulsar glitch mechanisms.

Findings

Estimated inner crust temperature of $0.9\times10^{8}$ K.

Identified persistent shifts contributing to long-term spin-down increase.

Braking index refined to $2.7(4)$ after glitch effects removal.

Abstract

PSR J0537$-$6910 is the most active glitching pulsar with a glitch rate $\sim0.3$ yr $^{-1}$. We have reanalysed 45 glitches of PSR J0537$-$6910 published in the literature and have done post-glitch timing fits within the vortex creep model. Moment of inertia fractions of the superfluid regions participating in glitches are obtained for each event and the model predictions for the inter-glitch time are confronted with the observed time-scales. Similarities and differences with the glitching behaviours of the well studied Crab and Vela pulsars are highlighted. From superfluid recoupling time-scales we estimate an inner crust temperature of $T=0.9\times10^{8}$ K for PSR J0537$-$6910. It is found that PSR J0537$-$6910 glitches leave behind persistent shifts similar to those observed from the Crab pulsar. These persistent shifts are responsible for the long term increase of the spin-down rate of PSR J0537$-$6910 and the apparent negative trend in its braking. Glitch magnitudes and persistent shifts of PSR J0537$-$6910 are consistent with the scenario that this is a young pulsar in the process of developing new vortex traps. We determine a braking index $n=2.7(4)$ after glitch induced contributions to the rotational evolution have been removed.