Active versus non-active galaxies: The seagull wings

Abstract

We have compared galaxies hosting an active nucleus with non-activegalaxies in the SDSS by analyzing their stellar populations. We concludethat the Seyfert 2 phenomenon appears in galaxies of intermediatemasses ({\tilde}2 {\times} 1010 M_{o}), while low mass galaxies donot produce active nuclei, and high mass galaxies tend to producea low level of non-stellar activity. We also compared the environmentof active and non-active galaxies of similar masses and concludedthat there is no excess of close neighbors among the Seyferts whencompared with non-active galaxies.