Fabrizio FIORE
(INAF-OAR)
Recent work combining mid-IR, near-IR and optical photometry with an X-ray stacking analysis claimed the detection of a large
population of highly obscured AGN in the COSMOS field. However, alternative explanations of the observed hard X-ray colors, although unlikely, cannot be ruled out.
The smoking gun of highly obscured AGN is the detection of strong iron 6.4 keV emission lines. To search for these features we obtained stacked images of the rest frame energy range 6-7 keV of the above MIPS galaxy samples, and compared them with images at lower and higher energies. We present preliminary results of this analysis.