1711.00481
The impact of environment on the stellar mass - halo mass relation
Golden-Marx, Miller
A large variance exists in the amplitude of the stellar mass - halo mass (SMHM) relation for group and cluster-size halos. Show that the magnitude gap between the BCG and its second or 4th brightest neighbor accounts for a significant portion of this variance. Find that at fixed halo mass, galaxy clusters with a higher magnitude gap have a higher BCG stellar mass. This relationship is also observed in semi-analytic representations of low-z galaxy clusters in simulations. This SMHM-magnitude gap stratification likely results from BCG growth via hierarchical mergers and may link assembly of the halo with the growth of the BCG. Using a Bayesian model, quantify the importance of the magnitude gap in the SMHM relation results in a large reduction in the inferred intrinsic scatter in the BCG stellar mass at fixed halo mass. Discuss the ramifications of this result in the context of galaxy formation models of centrals in group and cluster-sized halos.
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