| Description |
We have detected strong overdensities of submillimeter
galaxies (SMGs) around a sample of z~2 QSOs using SCUBA 450
and 850 micron maps. In at least one case we have proved
that most of those objects are indeed at the same redshift
as the QSO, and hence related to it. If the other SMGs are
also related to their entral QSOs they would represent high
density peaks in the density of the early Universe, where
present-day massive galaxies are thought to form. However,
our understanding of the origin of such emission (expected
to be due to thermal emission by dust heated by star
formation) is very sketchy, since we only have one or,
at best, two measurements of their far infra-red/submm
Spectral Energy Distribution.
Small scan maps with PACS and SPIRE on-board Herschel
would provide crucial data around the expected peak of
the emission for those SMGs, allowing an unambiguous
determination of its spectral shape and strength, and
hence proving its origin and providing accurate estimates
of the physical properties of the emitting dust. This
in turn can be used to quantify the star formation rates
and dust masses, to understand the evolutionary status of
these objects.
Additionally, the high-sensitivity Herschel maps would
probe the source counts around the QSOs in hitherto
unexplored bands to unprecedented depth, providing vital
clues to really understand the role of these objects in
the formation of galaxies in these early peaks in the
density of the Universe. |
