Context :

Aims : We aim at estimating the spectral energy distributions ( SEDs ) and the physical parameters related to the black holes harbored in eight high X-ray-to-optical ( { F _ { X } } / { F _ { R } } > 10 ) obscured quasars at z > 0.9 selected in the 2–10 keV band from the HELLAS2XMM survey .

Methods : We use IRAC and MIPS 24 \mu m observations , along with optical and K _ { s } -band photometry , to obtain the SEDs of the sources .
The observed SEDs are modeled using a combination of an elliptical template and torus emission ( using the phenomenological templates of Silva et al .
2004 ) for six sources associated with passive galaxies ; for two point-like sources , the empirical SEDs of red quasars are adopted .
The bolometric luminosities and the M _ { BH } - L _ { K } relation are used to provide an estimate of the masses and Eddington ratios of the black holes residing in these AGN .

Results : All of our sources are detected in the IRAC and MIPS ( at 24 \mu m ) bands .
The SED modeling described above is in good agreement with the observed near- and mid-infrared data .
The derived bolometric luminosities are in the range \approx 10 ^ { 45 } -10 ^ { 47 } erg s ^ { -1 } , and the median 2–10 keV bolometric correction is \approx 25 , consistent with the widely adopted value derived by Elvis et al .
( 1994 ) .
For the objects with elliptical-like profiles in the K _ { s } band , we derive high stellar masses ( 0.8 - 6.2 ) { \times } 10 ^ { 11 } M _ { \odot } , black hole masses in the range ( 0.2 - 2.5 ) { \times } 10 ^ { 9 } M _ { \odot } , and Eddington ratios L / L _ { Edd } < 0.1 , suggesting a low-accretion phase .

Conclusions :