Submillimetre observations of X-ray active galactic nuclei in the
  William Herschel Deep Field
  We investigate the contribution made by active galactic nuclei (AGN) to the
high-redshift, luminous, submillimetre (submm) source population using deep (<
2 mJy/beam) Large Apex Bolometer Camera (LABOCA) 870 um observations within the
William Herschel Deep Field (WHDF). This submm data complements previously
obtained Chandra X-ray data of the field, from which AGN have been identified
with the aid of follow-up optical spectra. From the LABOCA data, we detect 11
submm sources (based on a detection threshold of 3.2 sigma) with estimated
fluxes of > 3 mJy/beam. Of the 11 identified submm sources, we find that 2
coincide with observed AGN and that, based on their hardness ratios, both of
these AGN appear to be heavily obscured. We perform a stacking of the submm
data around the AGN, which we group by estimated column density, and find that
only the obscured (N_H > 10^22 cm^2) AGN show significant associated submm
emission. These observations support the previous findings of Page et al and
Hill et al that obscured AGN preferentially show submm emission. Hill et al
have argued that, in this case, the contribution to the observed submm emission
(and thus the submm background) from AGN heating of the dust in these sources
may be higher than previously thought.
