Dual-population radio source unification

Abstract

Space densities for radio sources are derived by considering the orientation paradigms unifying compact and extended radio sources. This new analysis shows how the change in form of source counts with frequency arises as a consequence of unification and accurately describes the observed decline in the fraction of core-dominated and broad-line objects with decreasing flux density. Source-count and identification data thus provide potent evidence in favour of orientation-dependent unified models for powerful radio sources.