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We present the X-ray spectral analysis of the 1855 extragalactic sources inthe Chandra COSMOS-Legacy survey catalog having more than 30 net counts in the0.5-7 keV band. 38% of the sources are optically classified Type 1 activegalactic nuclei (AGN), 60% are Type 2 AGN and 2% are passive, low-redshiftgalaxies. We study the distribution of AGN photon index and of the intrinsicabsorption N(H,z) based on the sources optical classification: Type 1 have aslightly steeper mean photon index than Type 2 AGN, which on the other handhave average intrinsic absorption ~3 times higher than Type 1 AGN. We find that~15% of Type 1 AGN have N(H,z)>1E22 cm^(-2), i.e., are obscured according tothe X-ray spectral fitting; the vast majority of these sources haveL(2-10keV)>$1E44 erg/s. The existence of these objects suggests that opticaland X-ray obscuration can be caused by different phenomena, the X-rayobscuration being for example caused by dust-free material surrounding theinner part of the nuclei. ~18% of Type 2 AGN have N(H,z)<1E22 cm^(-2), and mostof these sources have low X-ray luminosities (L(2-10keV)<$1E43 erg/s). Weexpect a part of these sources to be low-accretion, unobscured AGN lacking ofbroad emission lines. Finally, we also find a direct proportional trend betweenN(H,z) and host galaxy mass and star formation rate, although part of thistrend is due to a redshift selection effect.

The Chandra COSMOS-Legacy survey: Source X-ray spectral properties