2006/11/08 by C. P. Haines, Haines, C. P., A. Gargiulo +11
Engineering · #Material Science and Thermodynamics
paper · pdf · doi:10.48550/arxiv.astro-ph/0611264
We examine the origins of the bimodality observed in the global properties of\ngalaxies by comparing the environmental dependencies of star-formation for\ngiant and dwarf galaxy populations. Using Sloan Digital Sky Survey (SDSS) DR4\nspectroscopic data to create a volume-limited sample complete to M*+3, we find\nthat the environmental dependences of giant and dwarf galaxies are quite\ndifferent, implying fundamental differences in their evolution. Whereas the\nstar-formation histories of giant galaxies are determined primarily by their\nmerger history, resulting in passively-evolving giant galaxies being found in\nall environments, we show that this is not the case for dwarf galaxies. In\nparticular, we find that old or passive dwarf galaxies are only found as\nsatellites within massive halos (clusters, groups or giant galaxies), with none\nin the lowest density regions. This implies that star-formation in dwarf\ngalaxies must be much more resilient to the effects of mergers, and that the\nevolution of dwarf galaxies is primarily driven by the mass of their host halo,\nthrough effects such as suffocation, ram-pressure stripping or galaxy\nharassment.\n