Joanna Woo, Avishai Dekel, S. M. Faber, Kai Noeske, David C. Koo, Brian F. Gerke, Michael C. Cooper, Samir Salim, Aaron A. Dutton, Jeffrey Newman, Benjamin J. Weiner, Kevin Bundy, Christopher N. A. Willmer, Marc Davis, Renbin Yan
We study the dependence of star-formation quenching on galaxy masses and environ- ment, in the SDSS (z ~ 0.1) and the AEGIS (z ~ 1). We address stellar mass M*, halo mass Mh, density over the nearest N neighbours deltaN, and distance to the halo centre D. Quenching is defined by low star formation rate rather than red colour, since one third of red galaxies are star forming. The fraction of quenched galaxies predominantly depends on Mh, while for satellites it also depends on D. For centrals the quenched fraction depends only weakly on deltaN and M* at low z, and somewhat more at z ~ 1, when the quenched fraction and Mh are lower. For satellites, M*-dependent quenching is noticeable at high D, reflecting a quenching dependence on sub-halo mass for recently captured satellites. At small D, where satellites likely fell in long ago, quenching strongly depends on Mh, and not on M*. The Mh-dependence of quenching is consistent with theoretical wisdom where virial shock heating in massive haloes shuts down accretion and triggers ram-pressure stripping, causing quenching. The interpretation of deltaN depends on the number of observed group members compared to N, motivating the use of D as a better measure of local environment.
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http://arxiv.org/abs/1203.1625
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