THE ZURICH ENVIRONMENTAL STUDY (ZENS) OF GALAXIES IN GROUPS ALONG THE COSMIC WEB. V. PROPERTIES AND FREQUENCY OF MERGING SATELLITES AND CENTRALS IN DIFFERENT ENVIRONMENTS

Abstract

We use the Zurich Environmental Study database to investigate the environmental dependence of the merger fraction Gamma and merging galaxy properties in a sample of similar to 1300 group galaxies with M > 10(9.2)M(circle plus) and 0.05 < z < 0.0585. In all galaxy mass bins investigated in our study, we find that Gamma decreases by a factor of similar to 2-3 in groups with halo masses M-HALO > 10(13.5)M(circle plus) relative to less massive systems, indicating a suppression of merger activity in large potential wells. In the fiducial case of relaxed groups only, we measure a variation of Delta T/Delta log(M-HALO) similar to -0.07 dex(-1), which is almost independent of galaxy mass and merger stage. At galaxy masses > 10(10.2) M-circle plus, most mergers are dry accretions of quenched satellites onto quenched centrals, leading to a strong increase of Gamma with decreasing group-centric distance at thesemass scales. Both satellite and central galaxies in these high-mass mergers do not differ in color and structural properties from a control sample of nonmerging galaxies of equal mass and rank. At galaxy masses of < 10(10.2) M-circle plus where we mostly probe satellite-satellite pairs and mergers between star-forming systems close pairs (projected distance < 10-20 kpc) show instead similar to 2x enhanced (specific) star formation rates and similar to 1.5x larger sizes than similar mass, nonmerging satellites. The increase in both size and star formation rate leads to similar surface star formation densities in the merging and control-sample satellite populations.