Connections between galaxy mergers and Starburst: evidence from local Universe

Major mergers and interactions between gas-rich galaxies with comparable masses are thought to be the main triggers of starburst. In this work, we study, for a large stellar mass range, the interaction rate of the starburst galaxies in the local universe. We focus independently on central and satellite star forming galaxies extracted from the Sloan Digital Sky Survey. Here the starburst galaxies are selected in the star formation rate (SFR) stellar mass plane with SFR five times larger than the median value found for "star forming" galaxies of the same stellar mass. Through visual inspection of their images together with close companions determined using spectroscopic redshifts, we find that ~50% of the "starburst" populations show evident merger features, i.e., tidal tails, bridges between galaxies, double cores and close companions. In contrast, in the control sample we selected from the normal star forming galaxies, only ~19% of galaxies are associated with evident mergers. The interaction rates may increase by ~5% for the starburst sample and 2% for the control sample if close companions determined using photometric redshifts are considered. The contrast of the merger rate between the two samples strengthens the hypothesis that mergers and interactions are indeed the main causes of starburst.