The environment of Sy1, Sy2 & bright IRAS galaxies: the AGN/starburst connection.

We present a 3-dimensional study of the local (≤ 100 h−1 kpc) environment of Sy1, Sy2 and Bright IRAS Galaxies. For this purpose we use three galaxy samples (Sy1, Sy2, BIRG) located at high galactic latitudes as well as three control sample of non-active galaxies having the same morphological, redshift and diameter size distributions as the corresponding Seyfert or BIRG sample. Using the CfA2 and SSRS galaxy catalogues as well as our own spectroscopic observations, we find that the fraction of BIRGs with a close neighbour is significantly higher than that of their control sample. We also find that Sy2 galaxies demonstrate the same behaviour with BIRG galaxies but not with Sy1s which do not show any excess of companions with respect to their control sample galaxies. An additional analysis of the relation between FIR colours and activity type of the BIRGs 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. Our results support an evolutionary scenario leading from Starbursting to a Sy2 and finally to an un-obscured Sy1 galaxy, where close interactions play the role of the triggering mechanism.