Abstract
We investigate the environments of both X-ray and radio-loud active
galactic nuclei (AGN) within the UK Infrared Telescope (UKIRT) Infrared
Deep Sky Survey (UKIDSS) Ultra-deep Survey (UDS) using deep infrared
selection to sample the galaxy density field in the redshift range 1.0
≤z≤ 1.5. Using angular cross-correlation techniques we find that
both X-ray and radio-loud AGN preferentially reside in overdense
environments. We also find that both types of AGN cluster more strongly
with those galaxies classified as 'passive' rather than those that are
actively star forming. We infer clustering scalelengths comparable to
those of passive red galaxies, suggesting that typical AGN at these
epochs reside in dark matter haloes of mass M≳ 1013
M&sun;. A closer look at the small-scale environments of the
AGN reveals that the neighbouring galaxies of radio-loud AGN have U-B
colours more skewed towards the 'green valley' and the red sequence,
whereas the neighbours of X-ray AGN show no difference to the general
galaxy population. This suggests that although both AGN types live in
overdense environments, the radio-loud AGN may be preferentially located
in more evolved cluster cores, in a similar environment to low-powered
radio AGN in the local Universe.
Original language | English |
---|---|
Pages (from-to) | 2626-2636 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 415 |
DOIs | |
Publication status | Published - 1 Aug 2011 |