Fine classification of the emission-line spectra of active galaxies

Abstract

We refine the classification of galaxies by activity types based on a number of samples of objects having homogeneous optical medium resolution spectra from SDSS. SDSS spectra provide many spectral features and details that were not available before. Three diagnostic diagrams and eye examination have been used and the combined activity types have been derived. A fine classification scheme was developed, where QSOs have subtypes like Seyferts, Narrow Line QSOs are introduced, subclasses for Narrow Line Seyfert 1s are used and Composite spectrum objects have their subtypes. This classification scheme much better describes all fine details in the optical spectra and allows further study of active galaxies by the subtypes for better understanding the Unified model and the physical properties of AGN and Starbursts.