On the Clustering of Faint Red Galaxies
  Faint red galaxies in the Sloan Digital Sky Survey show a puzzling clustering
pattern in previous measurements. In the two-point correlation function (2PCF),
they appear to be strongly clustered on small-scales, indicating a tendency to
reside in massive haloes as satellite galaxies. However, their weak clustering
on large scales suggests that they are more likely to be found in low mass
haloes. The interpretation of the clustering pattern suffers from the large
sample variance in the 2PCF measurements, given the small volume of the
volume-limited sample of such faint galaxies. We introduce a method to improve
the clustering measurements of faint galaxies by making a full use of a
flux-limited sample to obtain volume-limited measurements with an increased
effective volume. In the improved 2PCF measurements, the fractional
uncertainties on large-scales drop by more than 40 per cent, and the strong
contrast between small-scale and large-scale clustering amplitudes seen in
previous work is no longer prominent. From halo occupation distribution
modelling of the measurements, we find that a considerable fraction of faint
red galaxies to be satellites in massive haloes, a senario supported by the
strong covariance of small-scale 2PCF measurements and the relative spatial
distribution of faint red galaxies and luminous galaxies. However, the
satellite fraction is found to be degenerate with the slope of the distribution
profile of satellites in inner haloes. We compare the modelling results with
semi-analytic model predictions and discuss the implications.
