ABSTRACT
The detection of a significant fraction of the highest redshift
quasars (z > 5) in the (sub-)mm wavelength range indicates that a
substantial amount of dust has been synthesized already during the
first billion year since the Big Bang. Recent 24 μm
observations with Spitzer have shown that very hot dust is present
close to the QSO core in most z > 5 quasars. However, both the
(sub-)mm and MIR observations can only catch tails of the dust
emission spectrum, at λ (rest) > 200 μm, and at λ (rest) < 5
μm, respectively. Measuring the peak of the dust emission,
expected to reach 10. . . 30 mJy around λ (rest) ∼ 50 μm (120
< λ (obs) < 700 μm), has been beyond the capabilities of FIR
satellites or ground-based sub-mm telescopes. Thus, critical
properties, such as FIR luminosity, dust temperatures and mass,
remain unconstrained. To improve on this situation, we will conduct
a Herschel Guaranteed Time Key
Programme (GT KP) to collect far-infrared and sub-millimeter
photometry of more than 100 high redshift quasars using the PACS and
SPIRE instruments. We plan to determine the SEDs of three samples of
QSOs:
- all z > 5 quasars known to date,
- a dozen radio loud quasars and galaxies at the highest redshifts, and
- 29 Broad Absorption Line (BAL) quasars together with a comparison
sample of 17 non-BAL QSOs at matching redshifts.
In addition, we
plan to obtain PACS spectroscopy of four very dust-rich and lensed
high-redshift QSOs and galaxies for spectral line diagnostics, which
will help to disentangle the contributions of AGN- and
starburst-heated dust and thus complement the SED-based study. We
will spend in total 165 hours of PACS GT in this key programme, 115
hours for the photometry with PACS and SPIRE, and 50 hours for the
FIR spectroscopy.
