X-ray analysis and broad-band properties of [NeV]-selected type 2 AGN

The study of type 2 AGN is fundamental to the understanding of the evolution phases of AGN and of their influence on galaxy evolution and to shed light on the origin of the XRB emission at E>30 keV. The goal of my master thesis project is the study of 94 [NeV]-selected type 2 AGN at z = 1 in the COSMOS field, through the analysis of their X-ray spectra and optical-to-far-IR SED. The use of the new X-ray data from the Chandra COSMOS Legacy catalogue extends the X-ray coverage of the COSMOS field and provides a more uniform coverage. We also aim at studying the hosts of type 2 AGN to characterize their parameters, like stellar mass and SFR, and investigate whether these galaxies are different from ``normal'' galaxies due to the AGN influence. Our analysis showed that at least half of the sources are heavily obscured AGN and at least 4% can be classified as CT objects. These new data will be used to improve the estimate of the fraction of CT AGN at z=1 and their contribution to the XRB. The use of a SED fitting code allowed us to separate the AGN emission, in particular the mid-IR emission ascribed to the obscuring torus, that provided us with an estimate of the AGN bolometric power, from the galaxy emission. We used the latter to estimate the stellar mass of the galaxy and the SFR. We compared our results with those expected from the ``main sequence'' galaxies and found that our sources do not differ significantly from “normal” galaxies, hence the AGN has, so far, a limited impact on the host-galaxy SF. We found good correlations between the AGN 12um and 2 - 10 keV luminosities and between the AGN bolometric luminosities derived from the SED fitting and those from the rest-frame 2 - 10 keV intrinsic luminosities. These correlations can be used to estimate the AGN power of sources for which X-ray data are either not available or too shallow. The entire work underlines the importance of a multi-wavelength approach to properly constrain the properties of type 2 AGN.