Apparent Jet Speed versus Optical Classification: An Effective Test of Unified Model in Powerful Radio Sources

Abstract

We have carried out some statistical tests of relativistic beaming and radio source orientation scenarios using optical class, apparent jet speed (βapp) and redshift (1+z) of a sample from Kellermann et al (2004) as orientation indicators. The final compilation consists of 96 sources. 11 FRII radio galaxies and 85 radio-loud quasars were used for the analyses. Our results show that quasars have higher apparent jet speed than galaxies with the respective mean values as 6.833 and 1.209. This result is consistent with the simple relativistic beaming and orientation-based unification hypotheses in which quasars are the beamed counterparts of powerful radio galaxies which form the isotropic parent population. In order to further test the unification scheme for these objects, correlation analysis of the observed parameters for the two optical classes was performed. The result shows strong evidence that FRII radio galaxies and quasars are intrinsically the same but appear different due to relativistic beaming and orientation effects.