The Size, Structure and Ionization of the Broad Line Region in NGC 3227
  Hubble Space Telescope (HST) spectroscopy of the Seyfert 1.5 galaxy, NGC
3227, confirms previous reports that the broad H-alpha emission line flux is
time variable, decreasing by a modest ~ 11% between 1999 and 2000 in response
to a corresponding ~ 37% decrease in the underlying continuum. Modeling the gas
distribution responsible for the broad H-alpha, H-beta and H-gamma emission
lines favors a spherically symmetric inflow as opposed to a thin disk. Adopting
a central black hole mass of 7.6 x 10^{6} Msun, determined from prior
reverberation mapping, leads to the following dimensions for the size of the
region emitting the broad H-alpha line; an outer radius ~ 90 l.d and an inner
radius ~ 3 l.d. Thus, the previously determined reverberation size for the
broad line region (BLR) consistently coincides with the inner radius of a much
larger volume of ionized gas. However, the perceived size of the BLR is an
illusion, a consequence of the fact that the emitting region is ionization
bounded at the outer radius and diminished by Doppler broadening at the inner
radius. The actual dimensions of the inflow remain to be determined.
Nevertheless, the steady state mass inflow rate is estimated to be ~ 10^{-2}
Msun/yr which is sufficient to explain the X-ray luminosity of the AGN in terms
of radiatively inefficient accretion. Collectively, the results challenge many
preconceived notions concerning the nature of BLRs in active galactic nuclei.
