Modeling color-dependent galaxy clustering in cosmological simulations
  We extend the subhalo abundance matching method to assign galaxy color to
subhalos. We separate a luminosity-binned subhalo sample into two groups by a
secondary subhalo property which is presumed to be correlated with galaxy
color. The two subsamples then represent red and blue galaxy populations. We
explore two models for the secondary property, namely subhalo assembly time and
local dark matter density around each subhalo. The model predictions for the
galaxy two-point correlation functions are compared with the recent results
from the Sloan Digital Sky Survey. We show that the observed color dependence
of galaxy clustering can be reproduced well by our method applied to
cosmological N-body simulations without baryonic processes. We then compare the
model predictions for the color-dependent galaxy-mass cross correlation
functions with the results from gravitational lensing observations. The
comparison allows us to distinguish the models, and also to discuss what
subhalo property should be used to assign color to subhalos accurately. We show
that the extended abundance matching method using the local dark matter density
as a color proxy provides an accurate description of the galaxy populations in
the local universe. We also study impacts of scatter in the local dark matter
density-color relations. Introducing scatter improves agreements of our model
predictions with the observed red and blue galaxy clustering and is needed to
explain observed correlation functions in finer color bins. Finally, we study
red galaxy fraction profiles in galaxy group- and cluster-sized halos and find
the red fraction profiles have a relatively strong dependence on our model
parameters. We argue that the red fraction profiles can be an important
observational clue, in addition to galaxy clustering and galaxy-galaxy lensing,
to explore the galaxy-(sub)halo connections.
