The Environment of Sy1, Sy2 & Bright IRAS Galaxies

TL;DR

This study investigates the local environments of Seyfert and Bright IRAS Galaxies, revealing that interactions influence galaxy activity and support an evolutionary sequence from starburst to Sy2 to Sy1.

Contribution

It provides a 3D analysis of galaxy environments, showing the role of interactions in galaxy evolution and distinguishing behaviors among different galaxy types.

Findings

BIRGs have more close neighbors than control galaxies.

Sy2 galaxies show similar interaction patterns to BIRGs.

Colors of non-interacting starbursts resemble Sy2s.

Abstract

We present a 3-dimensional study of the local (< 100 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 neighbor 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 colors and activity type of the BIRG's shows a significant difference between the colors of strongly-interacting and non-interacting starbursts and a resemblance between the colors of non-interacting starbursts and Sy2s.Our results support an evolutionary scenario leading from Starbursting to a Sy2 and finally to an unobscured Sy1 galaxy, where close interactions play the role of the triggering mechanism.