| Description |
The detection of a significant fraction of the highest redshift quasars (z >5) in the (sub-)mm wavelength range indicates that a substantial amount ofdust has been synthesized already during the first billion year since the BigBang. Recent 24 micron observations with Spitzer have shown that very hot dustis 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 emissionspectrum, at lambda_rest > 200 m, and at lambda_rest < 5 m,respectively. Measuring the peak of the dust emission, expected to reach 10. 30 mJy around lambda_rest virgul 50 m (120m < lambda_obs < 700m), has beenbeyond the capabilities of FIR satellites or ground-based sub-mmtelescopes. Thus, critical properties, such as FIR luminosity, dusttemperatures and mass, remain unconstrained.To improve on this situation, we propose a Herschel Guaranteed Time KeyProgramme (GT KP) to collect far-infrared and sub-millimeter photometry ofmore than 100 high redshift quasars using the PACS and SPIRE instruments. Weplan to determine the SEDs of three samples of QSOs: (i) all z > 5 quasarsknown to date, (ii) a dozen radio loud quasars and galaxies at the highestredshifts, and (iii) 29 Broad Absorption Line (BAL) quasars together with acomparison sample of 17 non-BAL QSOs at matching redshifts. In addition, weplan to obtain PACS spectroscopy of four very dust-rich and lensedhigh-redshift QSOs and galaxies for spectral line diagnostics, which will helpto disentangle the contributions of AGN- and starburst-heated dust and thuscomplement the SED-based study.We will spend in total 165 hours of PACS GT in this key programme, 115 hoursfor the photometry with PACS and SPIRE, and 50 hours for the FIR spectroscopy. |
