Do group dynamics play a role in the evolution of member galaxies?
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abstract
We examine galaxy groups from the present epoch to z = 1 to explore the
impact of group dynamics on galaxy evolution. We use group catalagues from the
Sloan Digital Sky Survey (SDSS), the Group Environment and Evolution
Collaboration (GEEC) and the high redshift GEEC2 sample to study how the
observed member properties depend on galaxy stellar mass, group dynamical mass
and dynamical state of the host group. We find a strong correlation between the
fraction of non-star-forming (quiescent) galaxies and galaxy stellar mass, but
do not detect a significant difference in the quiescent fraction with group
dynamical mass, within our sample halo mass range of 10^13-10^14.5 M_sun, or
with dynamical sate. However, at a redshift of approximately 0.4 we do see some
evidence that the quiescent fraction in low mass galaxies (log(M_star/M_sun) <
10.5) is lower in groups with substructure. Additionally, our results show that
the fraction of groups with non-Gaussian velocity distributions increases with
redshift to roughly z = 0.4, while the amount of detected substructure remains
constant to z = 1. Based on these results, we conclude that for massive
galaxies (log(M_star/M_sun_ > 10.5), evolution is most strongly correlated to
the stellar mass of a galaxy with little or no additional effect related to
either the group dynamical mass or dynamical state. For low mass galaxies, we
do see some evidence of a correlation between the quiescent fraction and the
amount of detected substructure, highlighting the need to probe further down
the stellar mass function to elucidate the role of the environment in galaxy
evolution.
