GOODS-Herschel: The far-infrared view of star formation in AGN host galaxies since z~3

Understand

We present a study of the infrared properties of X-ray selected, moderate luminosity (Lx=10^{42}-10^{44}ergs/s) active galactic nuclei (AGNs) up to z~3, to explore the links between star formation in galaxies and accretion onto their central black holes.

• We use 100um and 160um fluxes from GOODS-Herschel -the deepest survey yet undertaken by the Herschel telescope- and show that in >94 per cent of cases these fluxes are dominated by the host.
• We find no evidence of any correlation between the X-ray and infrared luminosities of moderate AGNs at any redshift, suggesting that star-formation is decoupled from nuclear (AGN) activity.
• The star formation rates of AGN hosts increase strongly with redshift; by a factor of 43 from z<0.1 to z=2-3 for AGNs with the same X-ray luminosities.