The warm Gaseous Disk and the Anisotropic Circumgalactic Medium of the
  Milky Way
  The warm ($\log~T\approx5$) gas is an important gaseous component in the
galaxy baryonic cycle. We built a 2-dimension disk-CGM model to study the warm
gas distribution of the Milky Way (MW) using the absorption line surveys of Si
IV and O VI. In this model, the disk component of both ions has the same
density profile ($n(r, z)=n_0\exp(-|z|/z_0)\exp(-r/r_0)$) with a scale height
of $z_0=2.6\pm0.4\rm~kpc$ and a scale length of $r_0=6.1\pm1.2\rm~kpc$. For
this disk component, we calculate the warm gas mass of
$\log(M/M_\odot)=(7.6\pm0.2)-\log\frac{Z}{Z_\odot}$. The similar disk density
profiles and total masses of Si IV and O VI-bearing gas set constraints on the
ionization mechanisms. We suggest that the warm gas disk might be dominated by
the Galactic fountain mechanism, which ejects and recycles gas to set both the
scale height and the scale length of the warm gas disk. The CGM component in
our model has a dependence on Galactic latitude with a higher column density
along the direction perpendicular to the Galactic plane ($b=90^\circ$) than the
column density along the radial direction ($b=0^\circ$). The column density
difference between these two directions is $0.82\pm0.32\rm~dex$ at $6.3\sigma$
for both ions. This difference may be due to the enrichment of Galactic
feedback to the entire CGM, or an additional interaction layer between the warm
gas disk and the CGM; existing data cannot distinguish between these two
scenarios. If this higher column density at $b=90^\circ$ is for the entire CGM,
the total warm CGM mass is
$\log(M/M_\odot)\approx(9.5-9.8)-\log\frac{Z}{0.5Z_\odot}$ within the MW virial
radius of $250\rm~kpc$.
