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The Nearest GHz Peaked-Spectrum Radio Galaxy, PKS 1718-649In this paper we identify PKS 1718-649, at a distance of 56 Mpc (z = 0.014; H(sub o) = 75 km/s/Mpc, q(sub o) = 0), as the nearest GHz peaked-spectrum (GPS) radio galaxy, more than four times closer than any previously known. Extensive observations at radio wavelengths with the Australia Telescope Compact Array, the Southern Hemisphere VLBI Experiment array, and the Swedish-ESO Submillimetre Telescope have allowed us to determine the properties of the radio source: PKS 1718-649 consists of two compact sub-pc-scale components separated by approximately 2 pc, the overall radio polarization is low, and the radio spectrum is peaked near 3 GHz. Order-of-magnitude agreement between the quantitative model for GPS sources of Bicknell et al. and the radio data we present, as well as data at optical wavelengths from the literature, raises the interesting possibility that PKS 1718-649 may be frustrated in its development by the nuclear environment of its host galaxy, NGC 6328. The model of Bicknell et al. suggests free-free absorption as an explanation of the PKS 1718-649 radio spectrum. However, both free-free absorption and synchrotron self-absorption mechanisms are plausible for this source and both may contribute to the overall radio spectrum. PKS 1718-649 provides evidence to strengthen the speculative suggestion that GPS sources arise as a consequence of galaxy merger activity.
Document ID
20010057600
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tingay, S. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Jauncey, D. L.
(Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Reynolds, J. E.
(Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Tzioumis, A. K.
(Commonwealth Scientific and Industrial Research Organization Epping, Australia)
King, E. A.
(Commonwealth Scientific and Industrial Research Organization Epping, Australia)
Preston, R. A.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Lovell, J. E.
(Tasmania Univ. Hobart, Australia)
McCulloch, P. M.
(Tasmania Univ. Hobart, Australia)
Costa, M. E.
(Tasmania Univ. Hobart, Australia)
Nicolson, G.
(Hartebeesthoek Radio Astronomy Observatory Johannesburg, South Africa)
Date Acquired
August 20, 2013
Publication Date
June 1, 1997
Publication Information
Publication: Astronomical Journal
Publisher: American Astronomical Society
Volume: 113
Issue: 6
ISSN: 0004-6256
Subject Category
Space Radiation
Distribution Limits
Public
Copyright
Other

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