Star formation in AGN hosts in GOODS-N
Berta, S.; Magnelli, B.; Nordon, R.; Lutz, D.; Altieri, B.; Andreani, P.; Aussel, H.; Cepa, J.; Cimatti, A.; Daddi, E.; Elbaz, D.; Förster Schreiber, N. M.; Genzel, R.; Maiolino, R.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Riguccini, L.; Rodighiero, G.; Sturm, E.; Tacconi, L. J.; Valtchanov, I.; Alexander, D. M.; Bauer, F. E.; Salvato, M.; Brandt, W. N.; Saintonge, A.; Rovilos, E.; Brusa, M.; Mainieri, V.; Santini, P.; Grazian, A.; Cava, A.; Bongiovanni, A.; Gruppioni, C.; Magdis, G.; Pérez García, A. M.; Sanchez Portal, M.; Shao, L.; Geis, N.; Wieprecht, E.; Wetzstein, M.; Dominguez-Sanchez, H.
Germany, Italy, United Kingdom, Spain, France, Chile, United States
Abstract
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 ≈ 1043 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} ⪉ 1044 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.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.