Masses of Black Holes in Active Galactic Nuclei: Implications for NLS1s
  I review how AGN black hole masses are calculated from emission-line
reverberation-mapping data, with particular attention to both assumptions and
caveats. I discuss the empirical relationship between AGN luminosity and
broad-line region radius that underpins the indirect methods by which most AGN
masses are estimated. I also discuss how line widths are characterized in this
method and illustrate how different ways of measuring the line-widths can lead
to systematic errors in the mass scale. I discuss specific implications for
NLS1 galaxies and consider whether the NLS1 phenomenon is better explained by
source inclination or by Eddington rate, and conclude that there is evidence
that both of these effects are contributing factors and that at least the
high-Eddington rate NLS1s are physically similar to some high-luminosity
quasars.
