ESA Science & Technology - No Clear Submillimeter Signature Of Suppressed Star Formation Among X-Ray Luminous Active Galactic Nuclei

Publication date: 02 November 2012

Authors: Harrison, C., et al.

Journal: The Astrophysical Journal Letters
Volume: 760
Issue: 1
Page: L15
Year: 2012

Copyright: IOP Publishing

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 >10⁴⁴ erg s^-1) at z ~ 1-3 in the Chandra Deep Field-North (CDF-N). In this Letter, we extend these results using Herschel-SPIRE 250 micron 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 >10⁴⁴ erg s^-1. On the basis of our analysis, we find no strong evidence for suppressed star formation in L_x >10⁴⁴ erg s^-1 AGNs at z ~ 1-3. The mean SFRs of the AGNs are constant over the broad X-ray luminosity range of L_x 10⁴³-10⁴⁵ erg s^-1 (with mean SFRs consistent with typical star-forming galaxies at z ~ 2; SFRs ~ 100-200 M_Sun 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.