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Castel Guelfo di Bologna, Italy

Lutz D.,MPE | Poglitsch A.,MPE | Altieri B.,European Space Astronomy Center | Andreani P.,European Southern Observatory | And 39 more authors.
Astronomy and Astrophysics | Year: 2011

Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. We describe the scientific motivation for the PACS Evolutionary Probe (PEP) guaranteed time key program and its role within the entire set of Herschel surveys, and the field selection that includes popular multiwavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, and EGS. We provide an account of the observing strategies and data reduction methods used. An overview of first science results illustrates the potential of PEP in providing calorimetric star formation rates for high-redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies. © 2011 ESO, .

Shao L.,MPE | Lutz D.,MPE | Nordon R.,MPE | Maiolino R.,National institute for astrophysics | And 44 more authors.
Astronomy and Astrophysics | Year: 2010

Sensitive Herschel far-infrared observations can break degeneracies that were inherent to previous studies of star formation in high-z AGN hosts. Combining PACS 100 and 160 μm observations of the GOODS-N field with 2 Ms Chandra data, we detect ∼20% of X-ray AGN individually at >3σ. The host far-infrared luminosity of AGN with L2-10 keV ≈ 10 43 erg s-1 increases with redshift by an order of magnitude from z = 0 to z ∼ 1. In contrast, there is little dependence of far-infrared luminosity on AGN luminosity, for L2-10∼ keV 10 44 erg s-1 AGN at z ≳ 1. We do not find a dependence of far-infrared luminosity on X-ray obscuring column, for our sample which is dominated by L2-10∼ keV}}$ < 1044 erg s -1 AGN. In conjunction with properties of local and luminous high-z AGN, we interpret these results as reflecting the interplay between two paths of AGN/host coevolution. A correlation of AGN luminosity and host star formation is traced locally over a wide range of luminosities and also extends to luminous high-z AGN. This correlation reflects an evolutionary connection, likely via merging. For lower AGN luminosities, star formation is similar to that in non-active massive galaxies and shows little dependence on AGN luminosity. The level of this secular, non-merger driven star formation increasingly dominates over the correlation at increasing redshift. © 2010 ESO.

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