Spectral nuclear properties of NLS1 galaxies
  It is not yet well known whether narrow line Seyfert 1 (NLS1) galaxies follow
the $M_{BH} - \sigma_{\star}$ relation found for normal galaxies. Emission
lines, such as [SII] or [OIII]$\lambda$5007, have been used as a surrogate of
the stellar velocity dispersion and various results have been obtained. On the
other hand, some active galactic nuclei (AGNs) have shown Balmer emission with
an additional intermediate component (IC) besides the well-known narrow and
broad lines. In order to re-examine the location of NLS1 in the $M_{BH} -
\sigma_{\star}$ relation, we test some emission lines, such as the narrow
component (NC) of H$\alpha$ and the forbidden [NII]$\lambda \lambda$6548,6584
and [SII]$\lambda \lambda$6716,6731 lines, as replacements for
$\sigma_{\star}$. On the other hand, we study the properties of the IC of
H$\alpha$ found in 14 galaxies of the sample to find a link between this
component, the central engine, and the remaining lines. We also compare the
emission among the broad component (BC) of H$\alpha$ and those emitted at the
narrow line region (NLR). We have obtained and studied medium-resolution
spectra (170 km s$^{-1}$ FWHM at H$\alpha$) of 36 NLS1 galaxies in the optical
range $\sim$5800 - 6800\AA. We found that, in general, most of the galaxies lie
below the $M_{BH} - \sigma_{\star}$ relation when the NC of H$\alpha$, [SII],
and [NII] lines are used as a surrogate of $\sigma_{\star}$. Besides this, we
found that 13 galaxies show an IC, most of which are in the velocity range
$\sim$ 700 $-$ 1500 km s$^{- 1}$. This is same range as in AGN types and is
well correlated with the FWHM of BC and, therefore, with the BH mass. On the
other hand, we found that there is a correlation between the luminosity of the
BC of H$\alpha$ and NC, IC, [NII]$\lambda$6584, and [SII] lines.
