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Timing observations of the Vela pulsar, PSR0833-45


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Klekociuk, AR 1989 , 'Timing observations of the Vela pulsar, PSR0833-45', PhD thesis, University of Tasmania.

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The analysis is presented of pulse arrival time measurements of the Vela
pulsar, PSR0833-45, obtained principally from near-daily observations conducted at
the Llanherne Radiophysics Observatory (LRO) between October, 1981, and
September, 1986. During this interval, the secular decrease in the rotation rate of the
pulsar was interrupted by glitch events which occurred in October, 1981, August,
1982, and July, 1985. Each glitch was accompanied by an abrupt change in rotation
frequency of fractional magnitude Aviv -2x10⁻⁶ of which less than 10% decayed
within a subsequent interval of one year. The characteristics of these events were
similar to those reported for the four previous glitches of the Vela pulsar. However,
because of the regularity of the LRO observations, sufficient post-jump data were
obtained to allow the reappraisal of the existing glitch models.
The timing obtained immediately prior to each glitch were found to be
completely devoid of any distinctive precursor signatures above the level of
measurement noise, even to within one hour of the July, 1985, glitch. In addition,
there were no significant changes in the characteristics of the radio emission about the
time of each glitch.
The timing signature of each glitch was investigated in terms of the existing
viable models. The two-component model was rejected on the grounds of its inability
to account for the long term relaxation behaviour. In addition, there was no evidence
of the decoupling time predicted by the vortex creep model.
The phase noise on timescales less than 6 hours was found to exhibit excess
power in comparison with the expectation from measurement uncertainties. There was
no evidence for any significant systematic behaviour of the autocorrelation function of
the phase fluctuations with respect to time lag. Evidence was found that the excess
noise has a power-law dependence on observing frequency, which may be a result of
magnetospheric processes.
Dual frequency measurements made between March and September, 1986,
have for the first time enabled the character of short timescale variations in the
dispersion delay along the path to the pulsar to be determined. The measurements are
consistent with the motion of the line-of-sight through a region of inhomogeneous
plasma located within the Gum Nebula.

Item Type: Thesis - PhD
Authors/Creators:Klekociuk, AR
Keywords: Pulsars
Copyright Holders: The Author
Copyright Information:

Copyright 1989 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1991. Includes bibliographical references (p. 264-274)

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