Giorgio LANZUISI
(DIFA-University of Bologna)
We exploit the rich multi-wavelength data set available in the COSMOS field for a large sample (~700 sources) of AGN and their hosts, in the redshift range 0.1<z<4. We use X-ray data to select AGN and determine their properties (LX and NH), and broad-band SED fitting to derive host galaxy properties (M* and SFR). We find that the average LIR_SF has a flat distribution in bins of AGN LX, while the average AGN LX increases in bins of host LIR_SF. We also discuss the comparison between the distribution of these two quantities and the predictions from hydro-dynamical simulations. Finally we find that the average NH shows a positive correlation with the host M*, at all redshifts, but not with the SFR. This translates into a negative correlation with sSFR. Our results are in agreement with the idea that BH accretion and SF are correlated, but occur with different variability time scales. The presence of a positive correlation between NH and host M* suggests that the X-ray obscuration is not entirely due to the circum-nuclear obscuring torus, but may also include a contribution from the host galaxy.