Warm Absorbers and Outflows in the Seyfert-1 Galaxy NGC 4051
  We present both phenomenological and more physical photoionization models of
the Chandra HETG spectra of the Seyfert-1 AGN NGC 4051. We detect 40 absorption
and emission lines, encompassing highly ionized charge states from O, Ne, Mg,
Si, S and the Fe L-shell and K-shell. Two independent photoionization packages,
XSTAR and Cloudy, were both used to self-consistently model the continuum and
line spectra. These fits detected three absorbing regions in this system with
densities ranging from 10^{10} to 10^{11} cm^{-3}. In particular, our XSTAR
models require three components that have ionization parameters of log \xi =
4.5, 3.3, & 1.0, and are located within the BLR at 70, 300, and 13,000 R_g,
respectively, assuming a constant wind density. Larger radii are inferred for
density profiles which decline with radius. The Cloudy models give a similar
set of parameters with ionization parameters of log \xi = 5.0, 3.6, & 2.2
located at 40, 200, and 3,300 R_g. We demonstrate that these regions are
out-flowing from the system, and carry a small fraction of material out of the
system relative to the implied mass accretion rate. The data suggest that
magnetic fields may be an important driving mechanism.
