The Evolutionary Sequence of AGN Activity

We concluded a 3-dimensional study of the local (<100kpc) environment of Seyfert 1 (Sy1), Seyfert 2 (Sy2) and Bright IRAS galaxies (BIRG) (Koulouridis et al. 2006a). For this purpose we used three galaxy samples (Sy1, Sy2, BIRG) located at high galactic latitudes and their corresponding control samples of non-active galaxies respecting the same morphological, redshift and diameter size distributions. Using the CfA2 and SSRS galaxy catalogues, as well as our own spectroscopic observations, we found that the fraction of Sy2 and BIRG galaxies with a close neighbour is significantly higher than that of their control sample. This is not true however for Sy1 galaxies which do not show any excess of companions with respect to their control sample galaxies. In addition, the relation between FIR colours and activity type of BIRG shows a significant difference between the colours of strongly-interacting and non-interacting Starbursts and a resemblance between the colours of non-interacting Starbursts and Sy2s (Koulouridis et al. 2006b).