The slow rise and recovery of the 2019 Crab pulsar glitch

TL;DR

This paper provides detailed measurements of the 2019 Crab pulsar glitch, revealing a delayed exponential spin-up and relaxation, offering insights into neutron star interior processes.

Contribution

It presents the first detailed observation of a delayed spin-up in the Crab pulsar glitch, enhancing understanding of neutron star interior dynamics.

Findings

Delayed exponential spin-up over 18 hours observed

Relaxation of rotation frequency occurred over approximately one week

First detailed measurement of this kind in Crab pulsar glitches

Abstract

We present updated measurements of the Crab pulsar glitch of 2019 July 23 using a dataset of pulse arrival times spanning $\sim$5 months. On MJD 58687, the pulsar underwent its seventh largest glitch observed to date, characterised by an instantaneous spin-up of $\sim$1 $\mu$Hz. Following the glitch the pulsar's rotation frequency relaxed exponentially towards pre-glitch values over a timescale of approximately one week, resulting in a permanent frequency increment of $\sim$0.5 $\mu$Hz. Due to our semi-continuous monitoring of the Crab pulsar, we were able to partially resolve a fraction of the total spin-up. This delayed spin-up occurred exponentially over a timescale of $\sim$18 hours. This is the sixth Crab pulsar glitch for which part of the initial rise was resolved in time and this phenomenon has not been observed in any other glitching pulsars, offering a unique opportunity to study the microphysical processes governing interactions between the neutron star interior and the crust.