| Description |
Massive clusters of galaxies have been found to date from as early as3-4 billion years after the Big Bang. Cosmological simulations using thecurrent cold dark matter model predict that these systems should descendfrom .proto-clusters. - early overdensities of massive galaxies thatmerge hierarchically to form a cluster. These protocluster regionsthemselves are built up hierarchically and so are expected to containextremely massive galaxies, progenitors of the quiescent behemothsobserved in cores of the present day massive galaxy clusters.Observational evidence for this picture, however, is sparse becausehigh-redshift proto-clusters are rare and difficult to observe. Here wepropose to probe with Herschel SPIRE the very beginning of the cluster andmassive galaxies formation process by observing 5 proto-clusters at 3<z<4.The aim of the project is to observe the entire Ultraluminous IR galaxy(ULIRG) population, dominating the bulk of the star formation at such highredshift, to compare the properties of the proto-cluster galaxies withthose of field galaxies at similar redshift. Determining whether clustergalaxies differ from field galaxies when the proto-cluster was stillforming, tells us whether any of the difference observed today is drivenby nature as apposed to nurture. |
