| Description |
Massive clusters of galaxies have been found to date from as early as
3-4 billion years after the Big Bang. Cosmological simulations using the
current cold dark matter model predict that these systems should descend
from .proto-clusters. - early overdensities of massive galaxies that
merge hierarchically to form a cluster. These protocluster regions
themselves are built up hierarchically and so are expected to contain
extremely massive galaxies, progenitors of the quiescent behemoths
observed in cores of the present day massive galaxy clusters.
Observational evidence for this picture, however, is sparse because
high-redshift proto-clusters are rare and difficult to observe. Here we
propose to probe with Herschel SPIRE the very beginning of the cluster and
massive 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 high
redshift, to compare the properties of the proto-cluster galaxies with
those of field galaxies at similar redshift. Determining whether cluster
galaxies differ from field galaxies when the proto-cluster was still
forming, tells us whether any of the difference observed today is driven
by nature as apposed to nurture. |
