Obscured AGNs in the Chandra COSMOS Survey

The Chandra COSMOS Survey (C-COSMOS) covers a large area ( 0.8 sq.deg.) to a considerable depth (2e-16 erg/cm2/s) in the soft (0.5-2 keV) band. This combination is optimized to detect a large population ( 43% of sources, 750) of X-ray sources in galaxies that lack the classic AGN emission line signatures. The rich multiwavelength COSMOS data set puts most of these at z 1-2. Are these sources starburst or AGN dominated? Or do they represent the 'starburst shrouded quasar' phase predicted by models? Being relatively bright, these 'galaxies' are easier to study than the similar, smaller, populations found in the Chandra Deep Fields. A spectral analysis of the brightest few dozen sources (Lanzuisi et al. 2010) have large obscuring X-ray column densities ( 10<SUP>(23)</SUP>cm<SUP>-2</SUP>), while stacking on the fainter objects show an increase in hardness ratio with increased L(24mu)/L(R) (Fiore et al. 2008), while a stacked spectrum, shifted to the rest frame, shows good evidence for a high EW Fe-K line (Fiore et al., 2010). An increasing number of red Keck/DEIMOS spectra show emission line signatures of both an AGN (NeV 3426A) and a starburst ([OII] 3727A) (Salvato et al., 2010). Interestingly the NeV lines are systematically blueshifted. This may be due to the quasar blowing away the host ISM, as models predict. The latest results will be presented. This work was supported in part by NASA Grant GO7-8136A.