Consistency of the black hole mass determination in AGN from the reverberation and the X-ray excess variance method

Abstract

Values of black hole masses are frequently determined with the help of the reverberation method. This method requires a specific geometrical factor related to the distribution of the orbits of the Broad Line Region clouds. Onken et al. determined the value f^2= 1.37+/-0.45 from the black hole mass - dispersion relation. In this paper we determine this factor using an independent mass determination from the X-ray variance method for a number of Seyfert 1 galaxies and comparing them with the reverberation results by Peterson et al. We obtain mean value f^2 = 1.12 +/- 0.54, consistent with Onken et al. Both values are larger than the value 0.75 corresponding to a spherical geometry. It indicates that most probably all values of the black hole masses obtained with the use of the Kaspi et al. formulae should be multiplied by a factor of \sim 1.7. This also shows that the Broad Line Region is rather flat, and hints for a dependence of the factor f^2 on a source inclination seem to be present in the data.