Giant Broad Line Regions in Dwarf Seyferts
  High angular resolution spectroscopy obtained with the Hubble Space Telescope
(HST) has revealed a remarkable population of galaxies hosting dwarf Seyfert
nuclei with an unusually large broad-line region (BLR). These objects are
remarkable for two reasons. Firstly, the size of the BLR can, in some cases,
rival those seen in the most luminous quasars. Secondly, the size of the BLR is
not correlated with the central continuum luminosity, an observation that
distinguishes them from their reverberating counterparts. Collectively, these
early results suggest that non-reverberating dwarf Seyferts are a heterogeneous
group and not simply scaled versions of each other. Careful inspection reveals
broad H Balmer emission lines with single peaks, double peaks, and a
combination of the two, suggesting that the broad emission lines are produced
in kinematically distinct regions centered on the black hole (BH). Because the
gravitational field strength is already known for these objects, by virtue of
knowing their BH mass, the relationship between velocity and radius may be
established, given a kinematic model for the BLR gas. In this way, one can
determine the inner and outer radii of the BLRs by modeling the shape of their
broad emission line profiles. In the present contribution, high quality spectra
obtained with the Space Telescope Imaging Spectrograph (STIS) are used to
constrain the size of the BLR in the dwarf Seyfert nuclei of M81, NGC 3998, NGC
4203, NGC 3227, NGC 4051, and NGC 3516.
