The distribution of galaxy morphological types and the morphology-mass   relation in different environments at low redshift
  We use \sim 2000 galaxies belonging to different environments to show how the fractions of different galaxy morphological types vary with global environment and as function of galaxy stellar mass at low redshift. Considering mass limited galaxy samples with log10 M\star/M\bigodot>= 10.25, we find a smooth increase/decline in the fraction of Es-S0s/late type galaxies going from single galaxies, to binaries, to groups. Considering all environments, the fractional variation is more conspicuous for S0s and late-types than for ellipticals solely due to a sharp enhancement/dearth of S0s/late-types in clusters compared to other environments. The morphological distribution of galaxies in the mass range 10.25 < log10 M\star/M\bigodot < 11 is rather independent both of galaxy stellar mass and global environment, except in clusters. The morphologies of galaxies more massive than log10 M\star/M\bigodot = 11 are instead a function of both galaxy mass and global environment. The morphology-mass relation therefore changes with global environment, showing that galaxy stellar mass cannot be the only parameter driving the morphological distribution of galaxies. The morphology-mass relations for S0 and late-type galaxies in clusters are peculiar compared to other environments, and this strongly suggests that cluster-specific effects act on these two types of galaxies, and that a significant number of S0s in clusters has a different origin with respect to S0s in other environments. 
Rosa Calvi, Bianca M. Poggianti, Giovanni Fasano, Benedetta Vulcani
astro-ph.CO