Probing the Anisotropy of the Milky Way Gaseous Halo-II: sightline
  toward Mrk509
  Hot, million degree gas appears to pervade the Milky way halo, containing a
large fraction of the Galactic missing baryons. This circumgalactic medium
(CGM) is probed effectively in X-rays, both in absorption and in emission. The
CGM also appears to be anisotropic, so we have started a program to determine
CGM properties along several sightlines by combining absorption and emission
measurements. Here we present the emission measure close to the \mrk509
sightline using new \suzaku and \xmm observations. We also present new analysis
and modeling of \chandra HETG spectra to constrain the absorption parameters.
The emission measure in this sightline is high,
EM$=0.0165\pm0.0008\pm0.0006~$cm$^{-6}~$pc, five times larger than the average.
The observed \ovii column density N(\ovii)$= 2.35\pm0.4 \times
10^{16}$cm$^{-2}$, however, is close to the average. We find that the
temperature of the emitting and absorbing gas is the same: $\log T (\rm K) =
6.33\pm0.01$ and $\log T (\rm K)=6.33\pm0.16$ respectively. We fit the observed
column density and emission measure with a $\beta-$model density profile. The
the central density is constrained to be between $n_0=2.8$--$6.0\times 10^{-4}$
cm$^{-3}$ and the core radius of the density profile has a lower limit of 40
kpc. This shows that the hot gas is mostly in the CGM of the galaxy, not in the
Galactic disk. Our derived density profile is close to the \citet{Maller2004}
profile for adiabatic gas in hydrostatic equilibrium with an NFW dark matter
potential well. Assuming this density profile, the minimum mass of the hot CGM
is $3.2 \times 10^{10}~$M$_{\odot}$.
