Different Angles on Active Galaxies: Where are We with Regard to Unification?

Abstract

With the realization that orientation plays a dominant role in the appearance of active galaxies, much of AGN research has been worked into the operating framework of the �unified scheme,� wherein active galaxies are broadly classified into three physically distinct classes: radio-quiet, radio-loud Fanaroff-Riley I and radio-loud Fanaroff-Riley II, with the appearance in each of the three cases being dominated by orientation alone. The following is a brief summary of the current understanding on the domain of validity of the scheme.