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Published December 5, 1995 | Published
Journal Article Open

Evolution of powerful extragalactic radio sources


Observations of complete flux density limited samples of powerful extragalactic radio sources by very-long-baseline interferometry enable us to study the evolution of these objects over the range of linear scales from 1 parsec to 15 kiloparsees (1 parsec = 3.09 x 10^(18) cm). The observations are consistent with the unifying hypothesis that compact symmetric objects evolve into compact steep-spectrum doubles, which in turn evolve into large-scale Fanaroff-Riley class II objects. It is suggested that this is the primary evolutionary track of powerful extragalactic radio sources. In this case there must be significant luminosity evolution in these objects, but little velocity evolution, as they expand from 1 parsec to several hundred kiloparsecs in overall size.

Additional Information

© 1995 National Academy of Sciences. This paper was presented at a colloquium entitled "Quasars and Active Galactic Nuclei: High Resolution Radio Imaging," organized by a committee chaired by Marshall Cohen and Kenneth Kellermann, held March 24 and 25, 1995, at the National Academy of Sciences Beckman Center, Irvine, CA. I thank Timothy Pearson, Antonis Polatidis, Gregory Taylor, Rene Vermeulen, Peter Wilkinson, and Wenge Xu for their contributions to this work over the course of the First Caltech-Jodrell Bank VLBI Survey. This work was supported by the National Science Foundation under Grants AST-9117100 and AST-9420018. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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Published - PNAS-1995-Readhead-11447-50.pdf


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