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We combine near-to-mid-IR Spitzer data with shorter wavelength observations(optical to X-rays) to get insights on the properties of a sample of luminous,obscured Active Galactic Nuclei (AGN). We aim at modeling their broad-bandSpectral Energy Distributions (SEDs) in order to estimate the main parametersrelated to the dusty torus. The sample comprises 16 obscured high-redshift(0.9<z<2.1) xray luminous quasars (L_2-10 ~ 10^44 erg s-1) selected from theHELLAS2XMM survey. The SEDs are described by a multi-component model includinga stellar component, an AGN component and a starburst. The majority (~80%) ofthe sources show moderate optical depth (tau_9.7um<3) and the derived columndensities N_H are consistent with the xray inferred values (10^22 <N_H< 3x10^23cm-2) for most of the objects, confirming that the sources are moderatelyobscured Compton-thin AGN. Accretion luminosities in the range 5x10^44 < Lbol <4x10^46 erg s-1 are inferred. We compare model luminosities with those obtainedby integrating the observed SED, finding that the latter are lower by a factorof ~2 in the median. The discrepancy can be as high as an order of magnitudefor models with high optical depth (tau_9.7um=10). The ratio between theluminosities obtained by the fitting procedure and from the observed SEDsuggest that, at least for Type~2 AGN, observed bolometric luminosities arelikely to underestimate intrinsic ones and the effect is more severe for highlyobscured sources. Bolometric corrections from the hard X-ray band are computedand have a median value of k_2-10kev ~ 20. The obscured AGN in our sample arecharacterized by relatively low Eddington ratios (median lambda_Edd~0.08). Onaverage, they are consistent with the Eddington ratio increasing at increasingbolometric correction (e.g. Vasudevan & Fabiam 2009).

The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN