This paper is the third in a series in which we present deep Chandra ACIS-S imaging spectroscopy of the Seyfert 1 galaxy NGC 4151 , devoted to study its complex circum-nuclear X-ray emission .
Emission features in the soft X-ray spectrum of the bright extended emission ( L _ { 0.3 - 2 { keV } } \sim 10 ^ { 40 } erg s ^ { -1 } ) at r > 130 pc ( 2″ ) are consistent with blended brighter OVII , OVIII , and NeIX lines seen in the Chandra HETGS and XMM-Newton RGS spectra below 2 keV .
We construct emission line images of these features and find good morphological correlations with the narrow line region clouds mapped in [ OIII ] \lambda 5007Å .
Self-consistent photoionization models provide good descriptions of the spectra of the large scale emission , as well as resolved structures , supporting the dominant role of nuclear photoionization , although displacement of optical and X-ray features implies a more complex medium .
Collisionally ionized emission is estimated to be \lesssim 12 % of the extended emission .
Presence of both low and high ionization spectral components and extended emission in the X-ray image perpendicular to the bicone indicates leakage of nuclear ionization , likely filtered through warm absorbers , instead of being blocked by a continuous obscuring torus .
The ratios of [ OIII ] /soft X-ray flux are approximately constant ( \sim 15 ) for the 1.5 kpc radius spanned by these measurements , indicating similar relative contributions from the low- and high-ionization gas phases at different radial distances from the nucleus .
If the [ OIII ] and X-ray emission arise from a single photoionized medium , this further implies an outflow with a wind-like density profile .
Using spatially resolved X-ray features , we estimate that the mass outflow rate in NGC 4151 is \sim 2 M _ { \odot } yr ^ { -1 } at 130 pc and the kinematic power of the ionized outflow is 1.7 \times 10 ^ { 41 } erg s ^ { -1 } , approximately 0.3 \% of the bolometric luminosity of the active nucleus in NGC 4151 .