- Georgakakis, A;
- Nandra, K;
- Laird, ES;
- Cooper, MC;
- Gerke, BF;
- Newman, JA;
- Croton, DJ;
- Davis, M;
- Faber, SM;
- Coil, AL
We explore the environment of z~1 AGN using a sample of 53 spectroscopically
identified X-ray sources in the All-wavelength Extended Groth strip
International Survey. We quantify the local density in the vicinity of an X-ray
source by measuring the projected surface density of spectroscopically
identified optical galaxies within a radius defined by the 3rd nearest
neighbour. Our main result is that X-ray selected AGN at z~1 avoid underdense
regions at the 99.89% confidence level. Moreover, although we find that the
overall population shares the same (rich) environment with optical galaxies of
similar U-B and M_B, there is also tentative evidence (96%) that AGN with blue
colors (U-B<1) reside in denser environments compared to optical galaxies. We
argue that the results above are a consequence of the whereabouts of massive
galaxies, capable of hosting supermassive black holes at their centers, with
available cold gas reservoirs, the fuel for AGN activity. At z~1 an increasing
fraction of such systems are found in dense regions.