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Evolution of the Parsec-Scale Structure of PKS 1934-638 Revisited: First Science with the ASKAP and New Zealand Telescopes


Tzioumis, AK and Tingay, SJ and Stansby, B and Reynolds, JE and Phillips, CJ and Amy, SW and Edwards, PG and Bowen, MA and Leach, MR and Kesteven, MJ and Chung, Y and Stevens, J and Forsyth, AR and Gulyaev, S and Natusch, T and Macquart, JP and Reynolds, C and Wayth, RB and Bignall, HE and Hotan, A and Hotan, C and Godfrey, L and Ellingsen, S and Dickey, J and Blanchard, J and Lovell, JEJ, Evolution of the Parsec-Scale Structure of PKS 1934-638 Revisited: First Science with the ASKAP and New Zealand Telescopes, Astronomical Journal, 140, (5) pp. 1506-1510. ISSN 0004-6256 (2010) [Refereed Article]

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© 2010. The American Astronomical Society. All rights reserved.

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DOI: doi:10.1088/0004-6256/140/5/1506


We have studied the archetypal Gigahertz Peaked Spectrum radio galaxy, PKS 1934−638, using the Australian Long Baseline Array augmented with two new telescopes that greatly improve the angular resolution of the array. These very long baseline interferometry observations represent the first scientific results from a new antenna in New Zealand and the first antenna of the Australian SKA Pathfinder. A compact double radio source, PKS 1934−638 has been monitored over a period of 40 years and the observation described here provides the latest datum, eight years after the previous observation, to aid in the study of the long-term evolution of the source structure. We take advantage of these new long baselines to probe PKS 1934−638 at the relatively low frequency of 1.4 GHz in order to examine the effects of optical depth on the structure of the radio source. Optical depth effects, resulting in the observation of frequency-dependent structure, may have previously been interpreted in terms of an expansion of the source as a function of time. Expansion and frequency-dependent effects are important to disentangle in order to estimate the age of PKS 1934−638. We show that frequency-dependent structure effects are likely to be important in PKS 1934−638 and present a simple two-dimensional synchrotron source model in which opacity effects due to synchrotron self-absorption are taken into account. Evidence for expansion of the radio source over 40 years is therefore weak with consequences for the estimated age of the radio source.

Item Details

Item Type:Refereed Article
Keywords:galaxies: individual (PKS 1934−638) – galaxies: structure – radio continuum: general
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Ellingsen, S (Professor Simon Ellingsen)
UTAS Author:Dickey, J (Professor John Dickey)
UTAS Author:Blanchard, J (Mr Jay Blanchard)
UTAS Author:Lovell, JEJ (Dr Jim Lovell)
ID Code:65420
Year Published:2010
Web of Science® Times Cited:9
Deposited By:Physics
Deposited On:2010-11-15
Last Modified:2015-02-10

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