Reverberation mapping of AGNs

Yet the reliability and accuracy of the method and the resulting mass estimates, M_BH_, remain uncertain. A recent study by Croom using a sample of Sloan Digital Sky Survey, 2dF QSO Redshift Survey, and 2dF-SDSS LRG and QSO Survey quasars suggests that line widths contribute little information about the BH mass in these SE estimates and can be replaced by a constant value without significant loss of accuracy.

In this Letter, we use a sample of nearby reverberation-mapped AGNs to show that this conclusion is not universally applicable. We use the bulge luminosity (L_Bulge_) of these local objects to test how well the known M_BH_-L_Bulge_correlation is recovered when using randomly assigned line widths instead of the measured ones to estimate M_BH_. We find that line widths provide significant information about M_BH_, and that for this sample, the line width information is just as significant as that provided by the continuum luminosities.