| Description |
We have detected strong overdensities of submillimetergalaxies (SMGs) around a sample of z~2 QSOs using SCUBA 450and 850 micron maps. In at least one case we have provedthat most of those objects are indeed at the same redshiftas the QSO, and hence related to it. If the other SMGs arealso related to their entral QSOs they would represent highdensity peaks in the density of the early Universe, wherepresent-day massive galaxies are thought to form. However,our understanding of the origin of such emission (expectedto be due to thermal emission by dust heated by starformation) is very sketchy, since we only have one or,at best, two measurements of their far infra-red/submmSpectral Energy Distribution.Small scan maps with PACS and SPIRE on-board Herschelwould provide crucial data around the expected peak ofthe emission for those SMGs, allowing an unambiguousdetermination of its spectral shape and strength, andhence proving its origin and providing accurate estimatesof the physical properties of the emitting dust. Thisin turn can be used to quantify the star formation ratesand dust masses, to understand the evolutionary status ofthese objects.Additionally, the high-sensitivity Herschel maps wouldprobe the source counts around the QSOs in hithertounexplored bands to unprecedented depth, providing vitalclues to really understand the role of these objects inthe formation of galaxies in these early peaks in thedensity of the Universe. |
