Photometric and clustering properties of hydrodynamical galaxies in a
  cosmological volume: results at z=0
  In this work, we present results for the photometric and clustering
properties of galaxies that arise in a LambdaCDM hydrodynamical simulation of
the local universe. The present-day distribution of matter was constructed to
match the observed large scale pattern of the IRAS 1.2-Jy galaxy survey. Our
simulation follows the formation and evolution of galaxies in a cosmological
sphere with a volume of ~130^3 (Mpc/h)^3 including supernova feedback, galactic
winds, photoheating due to an uniform meta-galactic background and chemical
enrichment of the gas and stellar populations. However, we do not consider
AGNs. In the simulation, a total of ~20000 galaxies are formed above the
resolution limit, and around 60 haloes are more massive than ~10^14 M_sun.
Luminosities of the galaxies are calculated based on a stellar population
synthesis model including the attenuation by dust, which is calculated from the
cold gas left within the simulated galaxies. Environmental effects like colour
bi-modality and differential clustering power of the hydrodynamical galaxies
are qualitatively similar to observed trends. Nevertheless, the overcooling
present in the simulations lead to too blue and overluminous brightest cluster
galaxies (BCGs). To overcome this, we mimic the late-time suppression of star
formation in massive halos by ignoring recently formed stars with the aid of a
simple post-processing recipe. In this way we find luminosity functions, both
for field and group/cluster galaxies, in better agreement with observations.
Specifically, the BCGs then follow the observed luminosity-halo mass relation.
However, in such a case, the colour bi-modality is basically lost, pointing
towards a more complex interplay of late suppression of star formation than
what is given by the simple scheme adopted.
