Modeling the Outflow in the Narrow-Line Region of Markarian
  573:Biconical Illumination of a Gaseous Disk
  We present a study of the outflowing ionized gas in the resolved narrow-line
region (NLR) of the Seyfert 2 galaxy Mrk 573, and its interaction with an in-
ner dust/gas disk, based on Hubble Space Telescope (HST) WFPC2 and STIS
observations. From the spectroscopic and imaging information, we determined the
fundamental geometry of the outflow and inner disk, via two modeling pro- grams
used to recreate the morphology of these regions imaged with HST. We also
determined that the bicone of ionizing radiation from the Active Galactic
Nucleus (AGN) intersects with the inner disk, illuminating a section of the
disk including inner segments of spiral arms, fully seen through structure
mapping, which appear to be outflowing and expanding. In addition, we see high
velocities at projected distances of \geq 2'' (- 700 pc) from the nucleus,
which could be due to rotation or to in situ acceleration of gas off the spiral
arms. We find that the true half opening angle of the ionizing bicone (53
degrees) is much larger than the apparent half-opening angle (34 degrees) due
to the above geometry, which may apply to a number of other Seyferts as well.
