A proto-cluster at z=2.45
  We present the spectroscopic confirmation of a $z=2.45$ proto-cluster. Its
member galaxies lie within a radius of 1.4Mpc (physical) on the sky and within
$\Delta v \pm 700$km/s along the line of sight. We estimate an overdensity of
10, suggesting that the structure has made the turn-around but is not assembled
yet. Comparison to the Millennium simulation suggests that analogous structures
evolve into $10^{14}-10^{15}$M$_{\odot}$/h type dark matter haloes by $z=0$
qualifying the notion of "proto-cluster". The search for the complete census of
mock progenitor galaxies at $z\sim2.5$ of these massive $z=0$ mock clusters
reveals that they are widely spread over areas with a diameter of 3-20Mpc. This
suggests that the optical selection of such proto-clusters can result in a rich
diversity regarding their $z=0$ descendants. We also searched for signs of
environmental differentiation in this proto-cluster. Whilst we see a weak trend
for more massive and more quiescent galaxies in the proto-cluster, this is not
statistically significant.
