The density field of the 10k zCOSMOS galaxies
  We use the current sample of ~10,000 zCOSMOS spectra of sources selected with
I(AB) < 22.5 to define the density field out to z~1, with much greater
resolution in the radial dimension than has been possible with either
photometric redshifts or weak lensing. We apply new algorithms that we have
developed (ZADE) to incorporate objects not yet observed spectroscopically by
modifying their photometric redshift probability distributions using the
spectroscopic redshifts of nearby galaxies. This strategy allows us to probe a
broader range of galaxy environments and reduce the Poisson noise in the
density field. The reconstructed overdensity field of the 10k zCOSMOS galaxies
consists of cluster-like patterns surrounded by void-like regions, extending up
to z~1. Some of these structures are very large, spanning the ~50 Mpc/h
transverse direction of the COSMOS field and extending up to Delta z~0.05 in
redshift. We present the three dimensional overdensity maps and compare the
reconstructed overdensity field to the independently identified virialised
groups of galaxies and clusters detected in the visible and in X-rays. The
distribution of the overdense structures is in general well traced by these
virialised structures. A comparison of the large scale structures in the
zCOSMOS data and in the mock catalogues reveals an excellent agreement between
the fractions of the volume enclosed in structures of all sizes above a given
overdensity between the data and the mocks in 0.2<z<1.
