Peculiar Glitch of PSR J1119-6127 and Extension of the Vortex Creep Model

TL;DR

This paper reports on a peculiar glitch in PSR J1119-6127 with associated emission changes and long-term spin-down rate decrease, extending the vortex creep model to explain these unusual features through starquake-induced inward vortex motion.

Contribution

The paper introduces an extension to the vortex creep model to account for unique glitch signatures and emission changes caused by starquakes in pulsars.

Findings

First observation of emission change coincident with a glitch.

Long-term decrease in the pulsar's spin-down rate.

Proposed starquake mechanism causes inward vortex motion.

Abstract

Glitches are sudden changes in rotation frequency and spin-down rate, observed from pulsars of all ages. Standard glitches are characterized by a positive step in angular velocity ($\Delta\Omega$ $ > $ $0$) and a negative step in the spin-down rate ($\Delta \dot \Omega$ $ < $ $0$) of the pulsar. There are no glitch-associated changes in the electromagnetic signature of rotation-powered pulsars in all cases so far. For the first time, in the last glitch of PSR J1119-6127, there is clear evidence for changing emission properties coincident with the glitch. This glitch is also unusual in its signature. Further, the absolute value of the spin-down rate actually decreases in the long term. This is in contrast to usual glitch behaviour. In this paper we extend the vortex creep model in order to take into account these peculiarities. We propose that a starquake with crustal plate movement towards the rotational poles of the star induces inward vortex motion which causes the unusual glitch signature. The component of the magnetic field perpendicular to the rotation axis will decrease, giving rise to a permanent change in the pulsar external torque.