No clear submillimeter signature of suppressed star formation among X-ray luminous active galactic nuclei

Abstract

Many theoretical models require powerful active galactic nuclei (AGNs) to suppress star formation in distant galaxies and reproduce the observed properties of today's massive galaxies. A recent study based on Herschel-SPIRE submillimeter observations claimed to provide direct support for this picture, reporting a significant decrease in the mean star formation rates (SFRs) of the most luminous AGNs (L X >1044ergs-1) at z1-3 in the Chandra Deep Field-North (CDF-N). In this Letter, we extend these results using Herschel-SPIRE 250 μm data in the COSMOS and Chandra Deep Field-South fields to achieve an order-of-magnitude improvement in the number of sources at L X >1044ergs-1. On the basis of our analysis, we find no strong evidence for suppressed star formation in L X >1044ergs-1 AGNs at z1-3. The mean SFRs of the AGNs are constant over the broad X-ray luminosity range of L X 1043-1045ergs-1 (with mean SFRs consistent with typical star-forming galaxies at z2; 〈SFRs〉 100-200 M yr-1). We suggest that the previous CDF-N results were likely due to low number statistics. We discuss our results in the context of current theoretical models. © 2012. The American Astronomical Society. All rights reserved..