  In our previous work, using luminosity and the H-beta FWHM as surrogates for
black hole mass (M_BH), we compared the black hole masses of narrow-line
Seyfert 1 galaxies (NLS1s) and broad-line Seyfert 1 galaxies (BLS1s) in a
sample of soft X-ray-selected active galactic nuclei. We found that the
distributions of black hole masses in the two populations are statistically
different. Recent work shows that the second moment of the H-beta emission line
(the line dispersion) is a better estimator of black hole mass than FWHM. To
test whether changing the width measure affects our results, we calculate line
dispersion-based black hole masses for our sample. We find that using the line
dispersion rather than the FWHM as a measure of the gas velocity shifts NLS1
and BLS1 virial product distributions closer together, but they remain
distinct. On the M_BH-sigma plane, we find that using the line dispersion
leaves NLS1s below the M_BH-sigma relation, but to a less significant degree
than when FWHM is used to calculate black hole masses (the [OIII] 5007A FWHM is
used as a surrogate for the bulge stellar velocity dispersion). The level of
significance of our findings is such that we cannot draw firm conclusions on
the location of the two samples on the M_BH-sigma plane. We are still left with
two alternative scenarios: either (1) NLS1s lie below the M_BH-sigma relation
indicating that their black hole masses are growing, or (2) NLS1s lie on the
M_BH-sigma relation, so they preferentially reside in smaller mass, less
luminous galaxies; the present data do not allow us to choose one over the
other. More trustworthy stellar velocity dispersions and accurate black hole
mass measurements are required for a firmer statement about the locus of NLS1s
on the M_BH-sigma plane.
