We study the Distant Red Galaxy ( DRG , J - K _ { s } > 2.3 ) neighbour population of Quasi Stellar Objects ( QSOs ) selected from the Sloan Digital Sky Survey ( SDSS ) in the redshift range 1 \leq z \leq 2 .
We perform a similar analysis for optically obscured AGNs ( i.e .
with a limiting magnitude I > 24 ) detected in the mid-infrared ( 24 \mu m ) with the Spitzer Space Telescope and a mean redshift z \sim 2.2 in the Flamingos Extragalactic Survey ( FLAMEX ) .
Both QSOs and obscured AGN target samples cover 4.7 deg ^ { 2 } in the same region of the sky .
We find a significant difference in the environment of these two target samples .
Neighbouring galaxies close to QSOs tend to be bluer than galaxies in optically obscured source environments .
We also present results on the cross–correlation function of DRGs around QSOs and optically faint mid-infrared sources .
The corresponding correlation length obtained for the QSO sample targets is r _ { 0 } = 5.4 \pm 1.6 Mpc h ^ { -1 } and a slope of \gamma = 1.94 \pm 0.10 .
For the optically obscured galaxy sample we find r _ { 0 } = 8.9 \pm 1.4 Mpc h ^ { -1 } and a slope of \gamma = 2.27 \pm 0.20 .
These results indicate that optically faint obscured sources are located in denser environment of evolved red galaxies compare to QSOs .