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Neutron Star Glitch

There was a recent news story about a periodic glitch  in the Vela  pulsar, observed in February, 2019.

The Vela pulsar is assumed to be a neutron star.

from Wikipedia:
'
Vela is the brightest pulsar (at radio frequencies) in the sky and spins 11.195 times per second (i.e. a period of 89.33 milliseconds—the shortest known at the time of its discovery). It has the third-brightest optical component of all known pulsars which pulses twice for every single radio pulse. The Vela pulsar is the brightest persistent object in the high-energy gamma-ray sky.
'

A pulsating gamma ray source as well as radio and optical must be synchrotron radiation to achieve that very high frequency.

Wikipedia (Vela Pulsar) has an image of its pulsar wind nebula.

This image looks like a plasmoid and even shows a very long jet of material ejecting along the central axis.

I had wondered how to justify proposing a plasmoid for a neutron star and this image begins that justification.
I do not know how to explain the 2:1 ratio of optical pulses to radio pulses.


The description of a glitch is always mechanical.

from a 2007 paper:

'
These nearly continuous timing records extend over 24 years allowing a greater insight into details of timing noise, micro glitches and other more exotic effects. In particular we report the glitch parameters of the 2004 event, along with the reconfirmation that the spin up for the Vela pulsar occurs instantaneously to the accuracy of the data. This places a lower limit of about 30 seconds for the acceleration of the pulsar to the new rotational frequency. We also confirm of the low braking index for Vela, and the continued fall in the DM for this pulsar.
'

My comment:

The instantaneous spin up is a mechanical problem for such a huge mass (assumed similar to Sun) in what is claimed to be a tiny sphere and then there is the obvious mechanical problem with braking.

I did not find a clear definition of micro glitch but I assume those are very brief deviations in the observed frequency followed by 'back to normal.'



from Feb 7, 2019 news story:

Following the discovery of a glitch of the Vela pulsar using radio observations (ATel# 12466), we report the detection and characterization of the glitch in data taken with the Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope. The glitch occurred while Vela was in the LAT field-of-view, and preliminary unbinned analysis of the 0.1-30 GeV photon data indicates the glitch at at Feb 1 2019 at 14:13:46 UTC, and that the amplitude of the spin frequency jump was 2.7867(6)x10^-5 Hz, similar to previously observed glitches. There is no strong evidence for changes in the pulse profile or additional transient features in the pulse timing, but we caution that unresolved transients can cause the glitch epoch uncertainty to be underestimated.
'

link



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