We use the Zurich ENvironmental Study ( ZENS ) database to investigate the environmental dependence of the merger fraction \Gamma and merging galaxy properties in a sample of \sim 1300 group galaxies with M > 10 ^ { 9.2 } \mbox { $M _ { \odot } $ } and 0.05 < z < 0.0585 .
In all galaxy mass bins investigated in our study , we find that \Gamma decreases by a factor of \sim 2 - 3 in groups with halo masses M _ { \mathrm { HALO } } > 10 ^ { 13.5 } ~ { } M _ { \odot } 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 \Delta \Gamma / \Delta \log ( M _ { \mathrm { HALO } } ) \sim - 0.07 dex ^ { -1 } , which is almost independent of galaxy mass and merger stage .
At galaxy masses > 10 ^ { 10.2 } ~ { } M _ { \odot } , most mergers are dry accretions of quenched satellites onto quenched centrals , leading to a strong increase of \Gamma with decreasing group-centric distance at these mass 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 < 10 ^ { 10.2 } ~ { } M _ { \odot } – where we mostly probe satellite–satellite pairs and mergers between star-forming systems – close pairs ( projected distance < 10 - 20 kpc ) show instead \sim 2 \times enhanced ( specific ) star formation rates and \sim 1.5 \times larger sizes than similar mass , nonmerging satellites .
The increase in both size and SFR leads to similar surface star-formation densities in the merging and control-sample satellite populations .