| Description |
The progenitors of local galaxy clusters (proto-clusters) are powerful laboratories for tracing the emergence of large scale structure and studying the evolution of galaxies in dense environments.We propose to use SPIRE.s excellent sensitivity and survey speed to obtain, for the first time, a large sample of dust-obscured, star forming, proto-cluster galaxies in an area encompassing the entire proto-cluster and its environment.The 8 proto-clusters in the sample cover the key redshift range 2 < z < 4 and have a wealth of existing, multi-wavelength data and a large number of spectroscopically confirmed proto-cluster galaxies. The masses of the proto-clusters are typically a few times 10^14 - 10^15 solar masses and the cores are up to 40 times denser than the field.Matching the SPIRE sources with upcoming LOFAR and EVLA radio observations, we will constrain the photometric redshifts to better than 0.3, resulting in a complete sample of dusty proto-cluster galaxies with very low (<5%) contamination.The proposed SPIRE observations will be compared to our extensive simulations of forming proto-clusters, allowing us to: (i) unveil and characterize the (dust-obscured) star-forming galaxies in the proto-clusters and constrain their star formations rates and dust temperature; (ii) relate these properties to their optical morphologies, stellar masses and location in the proto-cluster and investigate the differences between proto-cluster galaxies and field galaxies; (iii) ascertain whether red proto-cluster galaxies are passive galaxies or dusty starbursts; (iv) determine the structure and size of the proto-clusters, in particular, distinguish whether galaxies are distributed homogeneously or in filaments; (v) trace the evolution and contraction of large-scale structures from z=4 to z=2.The proto-cluster targets are ideally located for follow-up spectroscopy and high-resolution imaging with submm observatories such as APEX and ALMA. |
