Barthel's simple unification scheme of powerful radio galaxies and quasars, based entirely on the orientation dependent effects, has been confronted with the observed radio structures for 152 radio galaxies and 173 steep spectrum quasars. Contrary to the scheme's prediction, the cosmological evolution of geometrical parameters describing the large scale structure of these two types of radio sources is different. Linear size, arm ratio asymmetry and bending all are more strongly evolving with epoch for radio galaxies. Moreover, linear size and bending are more closely correlated with radio luminosity for radio galaxies than for quasars. This supports the supposition that, even if these two AGN classes are intrinsically identical sets of objects in deep interior regions, their large scale structures reveal various host environmental conditions that probably developed in the course of their evolution. In that case Barthel's simple unification scheme may be supplemented by additional class of less powerful objects with hardly visible broad line region even in their optical polarized flux spectrum.
The XXVIIth Young European Radio Astronomers Conference
- Pub Date:
- March 1995