The diagnostics and possible evolution in active galactic nuclei associated with starburst galaxies

Abstract

We present a large sample which contains 45 Seyfert1 galaxies (Sy1s), 46 hidden broad-line region (HBLR) Seyfert2 galaxies (Sy2s), 57 non-HBLR Sy2s, and 22 starburst galaxies to distinguish their properties and to seek the possible evolution of active galactic nuclei and starburst galaxies. We show that (1) using a plot of [O III] λ5007/Hα versus [N II] λ6584/ Hα of standard optical spectral diagnostic diagrams, it is found that an equation can separate non-HBLR Sy2s and HBLR Sy2s well; (2) the emission-line ratios and both the combination of the ratios and polycyclic aromatic hydrocarbon strength are utilized effectively to separate starburst galaxies and Seyfert galaxies; (3) by comparing a number of quantities from the data, we confirm well the separations with statistics; (4) on the basis of statistics, we suggest that HBLR Sy2s may be the counterparts of Sy1s at edge-on orientation. In addition, we discuss the possibility of starburst galaxies evolving to non-HBLR Sy2s and HBLR Sy2s and then evolving to Sy1s based on the statistical analysis. © 2011. The American Astronomical Society. All rights reserved.