Kinematic and Excitation Structure of the NGC 1068 Narrow-Line Region
  We investigated the kinematic and excitation structure of the NGC 1068
narrow-line region (NLR). We obtained profiles of several emission lines,
[OIII]$\lambda$5007, H$\beta$, [OI]$\lambda$6300 and [FeVII]$\lambda$6087 at
high-velocity resolution (R ~ 7500 - 11000), and confirmed that they showed
different profiles. These profiles are useful for understanding the NLR
structure, as they cover a wide ionization potential range. By comparing the
results with a photoionization model, we found that 1) blueshifted components
at the center are very dense, 2) those in the northeast region have slightly
lower densities than those in the center, and 3) ionization parameters of the
blueshifted components increase with increasing velocity with respect to the
systemic velocity. We investigated the NLR structure in NGC 1068 based on these
results. We show that both the observed velocity dependence of the ionization
parameter and the gradually increasing velocity field can be reproduced by
varying the ionizing continuum attenuation, assuming a hollowed biconical
geometry and varying the column densities of outflowing clouds.
