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Galactic X-ray sources and their radio counterparts.

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Duldig, M.(Marc) (1981) Galactic X-ray sources and their radio counterparts. PhD thesis, University of Tasmania.

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Abstract

A 5200 cm2 , xenon-filled, multiwire proportional counter
of 21 cm depth has been constructed for balloon-borne X-ray astronomy.
The telescope is sensitive to photons in the energy range 10 - 100 keV
and is surrounded on all sides, except the entrance window, by a
Sn/Cu graded shield and anti-coincidence guard counters. The counter
and 7° x 20 °FWHM collimator were contained within an hermetically
sealed aluminium pressure vessel of 1 metre diameter having expandable
mylar ends.
Counter pulses were pulse-height-analysed into 20 channels
and telemetered, together with count rate data (0.5 ms sample rate) and
house keeping data.
The telescope was equatorially mounted on a magnetically
referenced, reaction wheel servo-stabilized platform. Pointing under
ground control to within 0 05 of a specified source position was achieved
during flights in December 1976 and November 1978.
On line, quick-look, analysis of the telemetered data
with a PDP 11/10 computer enabled the observers to immediately assess the
telescope performance and attempt to rectify any problems by radio command.
A complete description of the telescope system and the
payload performance during balloon flights in December 1976 and November
1978 is presented. Problems encountered with outgassing of impurities
and the subsequent loss of resolution and gain are considered. Temporal
observations of VEL X-1, showing the 290s periodicity, and SCO X-1,
indicating rapid intensity variations, and spectral analyses of SCO X-1
are presented. More recent improvements to the telescope system are
also described.
Following the discovery of periodic radio flaring coincident
with sharp X-ray cutoffs from CIR X-1 a radio survey of 98 well determined
X-ray source positions at 14.7 GHz (λ=2cm) was undertaken using the
Parkes 64 m radio-telescope. Twelve radio counterparts, eight of which
are new, were detected and a further 81 upper limits were obtained.
Searches for variable radio emission correlated with X-ray events from
X-ray burst sources, as part of a world-wide 'Burst Watch', gave a null
result but enabled upper limits to the radio burst flux to be established.
Results from monitoring a complete flare of CIR X-1 showed a complex
triple peaked structure at λ = 2 cm. Observations carried out at 5 GHz
(λ=6cm) were combined with other published results to deduce a rate of
decrease for the orbital period of CIR X-1.
The implications of these observation are discussed with
particular reference to the recent eccentric orbit, luminosity-driven
shock model for radio emission from CIR X-1. The significance of the
other radio counterparts and selected upper limit results are also
considered.

Item Type: Thesis (PhD)
Keywords: X-ray astronomy, Radio astronomy
Copyright Holders: The Author
Copyright Information:

Copyright 1981 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, 1981. Bibliography: l. 166-

Date Deposited: 08 Dec 2014 23:55
Last Modified: 11 Mar 2016 05:56
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