Redshift and Luminosity Dependence of Linear Sizes of Compact Steep Spectrum Sources and the Quasar/Galaxy Unification Scheme

Abstract

We present and analyse plots of linear size–luminosity and linear size–redshift data for a sample of compact steep-spectrum sources (CSSs) and use them to investigate the currently popular but controversial orientation-based unification hypothesis for high-luminosity radio sources. This is based on the assumption that CSSs belong to a separate class of object. Our results show that the observed distributions of linear size (D) as a function of redshift (z) and radio luminosity (P) are in accord with the unified scheme in which CSS radio galaxies and CSS quasars are expected to be indistinguishable in their D−P/z correlations. This is particularly true when the two classes of object are properly matched in redshift. In the unification paradigm, both radio galaxies and quasars are expected to differ only in their orientation-dependent properties; all other properties should appear similar.