The ALHAMBRA survey: evolution of galaxy spectral segregation
  We study the clustering of galaxies as a function of spectral type and
redshift in the range $0.35 < z < 1.1$ using data from the Advanced Large
Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data
cover 2.381 deg$^2$ in 7 fields, after applying a detailed angular selection
mask, with accurate photometric redshifts [$\sigma_z < 0.014(1+z)$] down to
$I_{AB} < 24$. From this catalog we draw five fixed number density,
redshift-limited bins. We estimate the clustering evolution for two different
spectral populations selected using the ALHAMBRA-based photometric templates:
quiescent and star-forming galaxies. For each sample, we measure the real-space
clustering using the projected correlation function. Our calculations are
performed over the range $[0.03,10.0] h^{-1}$ Mpc, allowing us to find a
steeper trend for $r_p \lesssim 0.2 h^{-1}$ Mpc, which is especially clear for
star-forming galaxies. Our analysis also shows a clear early differentiation in
the clustering properties of both populations: star-forming galaxies show
weaker clustering with evolution in the correlation length over the analysed
redshift range, while quiescent galaxies show stronger clustering already at
high redshifts, and no appreciable evolution. We also perform the bias
calculation where similar segregation is found, but now it is among the
quiescent galaxies where a growing evolution with redshift is clearer. These
findings clearly corroborate the well known colour-density relation, confirming
that quiescent galaxies are mainly located in dark matter halos that are more
massive than those typically populated by star-forming galaxies.
