  Galactic winds play essential roles in the evolution of galaxies through the
feedback they provide. Despite intensive studies of winds, the radial
distributions of their properties and feedback are rarely observable. Here we
present such measurements for the prototypical starburst galaxy, M 82, based on
observations by Subaru telescope. We determine the radial distribution of
outflow densities ($n_e$) from the spatially-resolved [S II] $\lambda\lambda$
6717, 6731 emission-lines. We find $n_e$ drops from 200 to 40 cm$^{-3}$ with
radius ($r$) between 0.5 and 2.2 kpc with a best-fit power-law index of
$r^{-1.2}$. Combined with resolved H$\alpha$ lines, we derive mass, momentum,
and energy outflow rates, which drop quite slowly (almost unchanged within
error bars) over this range of $r$. This suggests that the galactic wind in M
82 can carry mass, momentum, and energy from the central regions to a few kpc
with minimal losses. We further derive outflow cloud properties, including size
and column densities. The clouds we measure have pressures and densities that
are too high to match those from recent theoretical models and numerical
simulations of winds. By comparing with a sample of outflows in local
star-forming galaxies studied with UV absorption-lines, the above-derived
properties for M 82 outflows match well with the published scaling
relationships. These matches suggest that the ionized gas clouds traced in
emission and absorption are strongly related. Our measurements motivate future
spatially resolved studies of galactic winds, which is the only way to map the
structure of their feedback effects.
