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Date and Time of the Query: 2019-06-25 T19:52:54 PDT
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For refcode 1990A&A...233..379S:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
1990A&A...233..379S Extended radio emission associated with GHz-peaked-spectrum radio sources C. Stanghellini, S .A. Baum, C. P. O'Dea, and G. B. Morris Istituto di Radioastronomia del CNR, Via Irnerio n. 46, I-40126 Bologna, Italy Netherlands Foundation for Research in Astronomy, Postbus 2, NL-7990 AA Dwingeloo, The Netherlands University of North Carolina, Chapel Hill, NC 27514, USA Received November 2, accepted December 13, 1989 Abstract. We observed a sample of 18 candidate GHz-Peaked-Spectrum (GPS) radio sources at 4 frequencies with the VLA in the A configuration. The original purpose of our observations was to obtain information on the general properties of the cores of these sources. However during the course of the data reduction we found that ~25% of the GPS sources exhibit diffuse extended emission near or around the core on the arcsecond scale. Thus the absence of extended emission can no longer be considered a defining characteristic of these sources. In this paper we present the images of these extended radio sources. The new evidence of extended emission associated with some of the GPS sources has significant implications for the nature of this class of objects. The short age (<~ 10^4^yr) suggested by the milliarcsecond structure is clearly in contrast with the presence of radio emission on linear scales of tens of kiloparsecs. The observations are consistent with two hypotheses suggested by Baum et al. for the compact double source 0108 + 388 which exhibits diffuse extended emission. The first is that the nuclear activity is recurrent and the compact radio source is propagating out amidst the relic of the previous epoch of activity. The second hypothesis is that an infall of gas and dust to the nucleus has smothered an existing radio source, temporarily confining it to the nucleus and cutting off the supply of energy to the extended structure. Key words: active galaxies - radio galaxies - polarization - quasars - radio sources
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