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

Banerji, Manda; McMahon, R.G.; Willott, C.J.; Geach, J.E.; Harrison, C.M.; Alaghband-Zadeh, S.; Alexander, D.M.; Bourne, N.; Coppin, K.E.K.; Dunlop, J.S.; Farrah, D.; Jarvis, M.; Michałowski, M.J.; Page, M.; Smith, D.J.B.; Swinbank, A.M.; Symeonidis, M.; van der Werf, P.P.

Abstract

We study the 850-μm emission in X-ray-selected active galactic nuclei (AGN) in the ∼2 deg2 COSMOS field using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850-μm bright X-ray AGN in a ‘high-sensitivity’ region covering 0.89 deg2 with flux densities of S850 = 4–10 mJy. The 19 AGN span the full range in redshift and hard X-ray luminosity covered by the sample – 0.7 ≲ z ≲ 3.5 and 43.2 ≲ log10(LX) ≲ 45. We report a highly significant stacked 850-μm detection of a hard X-ray flux-limited population of 699 z > 1 X-ray AGN – S850 = 0.71 ± 0.08 mJy. We explore trends in the stacked 850-μm flux densities with redshift, finding no evolution in the average cold dust emission over the redshift range probed. For type 1 AGN, there is no significant correlation between the stacked 850-μm flux and hard X-ray luminosity. However, in type 2 AGN the stacked submillimeter flux is a factor of 2 higher at high luminosities. When averaging over all X-ray luminosities, no significant differences are found in the stacked submillimeter fluxes of type 1 and type 2 AGN as well as AGN separated on the basis of X-ray hardness ratios and optical-to-infrared colours. However, at log10(L2 − 10/erg s−1) > 44.4, dependences in average submillimeter flux on the optical-to-infrared colours become more pronounced. We argue that these high-luminosity AGN represent a transition from a secular to a merger-driven evolutionary phase where the star formation rates and accretion luminosities are more tightly coupled. Stacked AGN 850-μm fluxes are compared to the stacked fluxes of a mass-matched sample of K-band-selected non-AGN galaxies. We find that at 10.5

Citation

Banerji, M., McMahon, R., Willott, C., Geach, J., Harrison, C., Alaghband-Zadeh, S., …van der Werf, P. (2015). Cold dust emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: dependence on luminosity, obscuration and AGN activity. Monthly Notices of the Royal Astronomical Society, 454(1), 419-438. https://doi.org/10.1093/mnras/stv1881

• Journal Article Type: Article
• Acceptance Date: Aug 12, 2015
• Online Publication Date: Sep 22, 2015
• Publication Date: Nov 21, 2015
• Deposit Date: Feb 9, 2016
• Publicly Available Date: Feb 12, 2016
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 454
• Issue: 1
• Pages: 419-438
• DOI: https://doi.org/10.1093/mnras/stv1881
• Keywords: Quasars: general, X-rays: galaxies, Galaxies: evolution, Submillimetre: galaxies.