Bolometric luminosities and Eddington ratios of X-ray selected active galactic nuclei in the<i>XMM</i>-COSMOS survey

Abstract

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