Black-hole masses of type 1 AGN in the XMM-Newton bright serendipitous survey.

Aims. We derive masses of the central supermassive black hole (SMBH) and accretion rates for 154 type 1 AGN belonging to a well-defined X-ray-selected sample, the XMM-Newton serendipitous sample (XBS). Methods. We used the most recent "single-epoch" relations, based on Hβ and MgIIλ2798 Å emission lines, to derive the SMBH masses.We then used the bolometric luminosities, computed on the basis of an SED-fitting procedure, to calculate the accretion rates, both absolute and normalized to the Eddington luminosity (Eddington ratio). Results. The selected AGNs cover a range of masses from 107 to 1010 M⊕ with a peak around 8 × 108 M⊕ and a range of accretion rates from 0.01 to ∼50 M⊕/year (assuming an efficiency of 0.1), with a peak at ∼1 M⊕/year. The values of Eddington ratio range from 0.001 to ∼0.5 and peak at 0.1. [ABSTRACT FROM AUTHOR]