Bolometric luminosities and Eddington ratios of X-ray selected Active
  Galactic Nuclei in the XMM-COSMOS survey
  Bolometric luminosities and Eddington ratios of both X-ray selected
broad-line (Type-1) and narrow-line (Type-2) AGN from the XMM-Newton survey in
the COSMOS field are presented. The sample is composed by 929 AGN (382 Type-1
AGN and 547 Type-2 AGN) and it covers a wide range of redshifts, X-ray
luminosities and absorbing column densities. About 65% of the sources are
spectroscopically identified as either Type-1 or Type-2 AGN (83% and 52%
respectively), while accurate photometric redshifts are available for the rest
of the sample. The study of such a large sample of X-ray selected AGN with a
high quality multi-wavelength coverage from the far-infrared (now with the
inclusion of Herschel data at 100 micron and 160 micron) to the optical-UV
allows us to obtain accurate estimates of bolometric luminosities, bolometric
corrections and Eddington ratios. The kbol-Lbol relations derived in the
present work are calibrated for the first time against a sizable AGN sample,
and rely on observed redshifts, X-ray luminosities and column density
distributions. We find that kbol is significantly lower at high Lbol with
respect to previous estimates by Marconi et al. (2004) and Hopkins et al.
(2007). Black hole masses and Eddington ratios are available for 170 Type-1
AGN, while black hole masses for Type-2 AGN are computed for 481 objects using
the black hole mass-stellar mass relation and the morphological information. We
confirm a trend between kbol and lambda_Edd, with lower hard X-ray bolometric
corrections at lower Eddington ratios for both Type-1 and Type-2 AGN. We find
that, on average, Eddington ratio increases with redshift for all Types of AGN
at any given Mbh, while no clear evolution with redshift is seen at any given
Lbol.
