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 Δv±700km/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 1014−1015M⊙/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∼2.5 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.
@article{arxiv.1411.0649,
title = {A proto-cluster at z=2.45},
author = {C. Diener and S. Lilly and C. Ledoux and G. Zamorani and D. Murphy and M. Bolzonella and P. Capak and O. Ilbert and H. McCracken},
journal= {arXiv preprint arXiv:1411.0649},
year = {2015}
}