Alteration of the magnetosphere of the Vela pulsar during a glitch


As pulsars lose energy, primarily in the form of magnetic dipole radiation, their rotation slows down accordingly. For some pulsars, this spin-down is interrupted by occasional abrupt spin-up events known as glitches1. A glitch is hypothesized to be a catastrophic release of pinned vorticity2 that provides an exchange of angular momentum between the superfluid outer core and the crust. This is manifested by a minute alteration in the rotation rate of the neutron star and its co-rotating magnetosphere, which is revealed by an abrupt change in the timing of observed radio pulses. Measurement of the flux density, polarization and single-pulse arrival times of the glitch with high time resolution may reveal the equation of state of the crustal superfluid, its drag-to-lift ratio and the parameters that describe its friction with the crust3. This has not hitherto been possible because glitch events happen unpredictably. Here we report single-pulse radio observations of a glitch in the Vela pulsar, which has a rotation frequency of 11.2 hertz. The glitch was detected on 2016 December 12 at 11:36 universal time, during continuous observations of the pulsar over a period of three years. We detected sudden changes in the pulse shape coincident with the glitch event: one pulse was unusually broad, the next pulse was missing (a ‘null’) and the following two pulses had unexpectedly low linear polarization. This sequence was followed by a 2.6-second interval during which pulses arrived later than usual, indicating that the glitch affects the magnetosphere.

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Fig. 1: Timing residuals of single pulses near the time of the glitch.
Fig. 2: A contiguous sequence of single pulses surrounding the ‘null’.
Fig. 3: Scatter plot of the mean and standard deviation of single-pulse timing residuals.
Fig. 4: Timing residuals and their cumulative sum around the time of the glitch.
Fig. 5: Peak flux density around the time of the ‘null’.


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We thank the staff at the School of Physical Sciences of the University of Tasmania who assisted in the observing programme. J.P. especially thanks B. Reid, E. Baynes and B. Bedson for on-site support at the 26-m and 30-m radio telescopes. J.P. also thanks N. Bochenek and W. Kean Tai for assisting in the searches of previous ‘nulls’. We acknowledge the Australian Government Research Training Program Scholarship, which helped fund this research, and the Tasmanian Partnership for Advanced Computing (TPAC) at the University of Tasmania, which is funded by the Australian Government through its NCRIS and RDSI programmes, for use of the 2.3-PB storage facility.

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Nature thanks J. Cordes and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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J.P. conducted all the observations, led the analysis and the writing of the manuscript and produced all the plots. J.M.D. provided input on the manuscript and analysis. W.v.S. conducted the polarization calibration and assisted with the manuscript and analysis. S.E. and A.H. assisted with the manuscript and analysis.

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Correspondence to Jim Palfreyman.

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Extended data figures and tables

Extended Data Table 1 Arrival times of the 2016 glitch of the Vela pulsar
Extended Data Table 2 Arrival times of key events at the Solar System barycentre

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Palfreyman, J., Dickey, J.M., Hotan, A. et al. Alteration of the magnetosphere of the Vela pulsar during a glitch. Nature 556, 219–222 (2018).

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