Ionization Mechanisms in Quasar Outflows
  The various ionization mechanisms at play in active galactic nuclei (AGN) and
quasars have been well studied, but relatively little has been done to
separately investigate the contributions of these ionization mechanisms within
the host galaxy and outflowing components. Using Gemini integral field
spectroscopy (IFS) data, we study the ionization properties of these two
components in four nearby ($z \lesssim$ 0.2) radio-quiet Type 1 quasars.
Emission line ratios and widths are employed to identify the dominant
ionization mechanisms for the host and outflow components in each object. We
find that photoionization by the AGN often dominates the ionization of both
gaseous components in these systems. In three cases, the outflowing gas is more
highly ionized than the gas in the host, indicating that it is more strongly
exposed to the ionizing radiation field of the AGN. In two objects, a positive
correlation between the line widths and line ratios in the outflowing gas
component indicates that shocks with velocities of order 100 $-$ 500 km
s$^{-1}$ may also be contributing to the ionization and heating of the
outflowing gas component. The line ratios in the outflowing gas of one of these
two objects also suggest a significant contribution from photoionization by
hot, young stars in the portion of the outflow that is closest to star-forming
regions in the host galaxy component. The data thus favor photoionization by
hot stars in the host galaxy rather than stars formed in the outflow itself.
