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 > 10 44 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 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 > 10 44 erg s −1 . On the basis of our analysis, we find no strong evidence for suppressed star formation in L X > 10 44 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 ≈ 10 43 -10 45 erg s −1 (with mean SFRs consistent with typical star-forming galaxies at z ≈ 2; 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.

Observational evidence that positive and negative AGN feedback depends on galaxy mass and jet power

“…These results argue for a scenario in which powerful quasars, on average, have not yet suppressed the star formation in the host galaxy (see e.g. Harrison et al 2012;Rosario et al 2013;Stanley et al 2015 but also e.g. Page et al 2012).…”

“…Shao et al 2010;Harrison et al 2012;Mullaney et al 2012b;Rovilos et al 2012;Santini et al 2012;Rosario et al 2013). They suggest that the sSFRs of AGN are consistent with those of star-forming galaxies, with possible exceptions the luminous AGN (e.g.…”

“…However, the picture is still not clear, with investigations at different wavelengths producing many differences of opinion as to the amount of radiation that is absorbed and reprocessed by dust, how this is related to the host galaxy and whether the triggering mechanism behind the AGN activity is also responsible for massive c 2012 RAS star-formation activity (e.g. Harrison et al 2012;Mullaney et al 2012b,a;Rodighiero et al 2015). Moreover, it is also unclear how these processes depend on luminosity and radio-loudness and how they are observationally affected by orientation (e.g.…”

Cold dust emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: dependence on luminosity, obscuration and AGN activity

“…Several recent studies have found a reasonably flat relationship between AGN luminosity and SFR (e.g. Harrison et al 2012;Rosario et al 2012;Azadi et al 2015;Stanley et al 2015). At modest X-ray luminosities where large samples of X-ray AGN with far-infrared and submillimeter data now exist, these results are now robust.…”

“…More recently, new data at far-infrared wavelengths from the Herschel Space Observatory, has been used to study the connection between star formation in galaxies and accretion on to the central AGN (e.g. Lutz et al 2008;Shao et al 2010;Bonfield et al 2011;Harrison et al 2012;Mullaney et al 2012;Page et al 2012;Rosario et al 2012;Rovilos et al 2012;Santini et al 2012;Azadi et al 2014;Stanley et al 2015). Lutz et al (2010) have also conducted a study of the 870-μm properties of z ∼ 1 AGN using LABOCA.…”