Rotational evolution of the Vela pulsar during the 2016 glitch

Abstract

The 2016 Vela glitch observed by the Mount Pleasant radio telescope provides the first opportunity to study pulse-to-pulse dynamics of a pulsar glitch, opening up new possibilities to study the neutron star’s interior. We fit models of the star’s rotation frequency to the pulsar data, and present the following three results. First, we constrain the glitch rise time to less than 12.6 s with 90% confidence, almost three-times shorter than the previous best constraint. Second, we find definitive evidence for a rotational-frequency overshoot and fast relaxation following the glitch. Third, we find evidence for a slowdown of the star’s rotation immediately before the glitch. The overshoot is predicted theoretically by some models; we discuss implications of the glitch rise and overshoot decay times on internal neutron-star physics. The slowdown preceding the glitch is unexpected; we propose the slowdown may trigger the glitch by causing a critical lag between crustal superfluid and the crust.

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Fig. 1: Rotational frequency evolution.
Fig. 2: Posterior distribution p(τr) for the glitch rise time, τr.
Fig. 3: Rotational frequency evolution of the data (black and grey reproduced from Fig. 1) and best-fit models.
Fig. 4: Posterior for overshoot–decay parameters in the H2+p model, corresponding to the red curves in Fig. 3.
Fig. 5: Posterior for precursor parameters in the H2+p model, corresponding to the red curves in Fig. 3.

Data availability

The data used in this work are available from ref. 2.

Code availability

The bilby19 analysis code is available from https://git.ligo.org/lscsoft/bilby and particular scripts for this analysis are available on request from the authors.

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Acknowledgements

We are grateful to A. Melatos and I. Jones for valuable comments. Computations were performed on the OzStar supercomputer. P.D.L. is supported through an Australian Research Council Future Fellowship FT160100112 and Discovery Project DP180103155. V.G. is supported by a McGill Space Institute postdoctoral fellowship and the Trottier Chair in Astrophysics and Cosmology.

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G.A. was responsible for the data analysis. G.A., P.D.L. and V.G. were responsible for the model development and discussion. J.P. was responsible for the data collection and reduction.

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Correspondence to Gregory Ashton.

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Ashton, G., Lasky, P.D., Graber, V. et al. Rotational evolution of the Vela pulsar during the 2016 glitch. Nat Astron 3, 1143–1148 (2019). https://doi.org/10.1038/s41550-019-0844-6

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