Deep X-ray surveys provide the most efficient identification of Active Galactic Nuclei ( AGN ) activity .
However , recent evidence has indicated that the current < 10 keV surveys do not detect the most heavily obscured AGNs .
Here we explore whether the X-ray undetected AGN population can be identified within the ultra-deep Spitzer survey of the GOODS-N field using X-ray stacking techniques .
We find evidence for AGN activity in the Spitzer dataset and the strongest and hardest X-ray signal is produced by galaxies with starburst-like infrared spectral slopes and median properties of z \approx 0.8 and L _ { IR } \approx 10 ^ { 11 } L _ { \odot } .
The stacked X-ray properties suggest that obscured AGN activity is present in these sources , with a median X-ray spectral slope of \Gamma \approx 1 and L _ { X } \approx 10 ^ { 42 } erg s ^ { -1 } .
These overall properties are consistent with the obscured AGN population expected to produce the unresolved X-ray background .