Molecular Gas within the Milky Way's Nuclear Wind
  We report the first direct detection of molecular hydrogen associated with
the Galactic nuclear wind. The Far-Ultraviolet Spectroscopic Explorer spectrum
of LS 4825, a B1 Ib-II star at $l,b$ = 1.67$^{\circ}$,$-$6.63$^{\circ}$ lying
$d$ = 9.9$^{+1.4}_{-0.8}$ kpc from the Sun, $\sim$1 kpc below the Galactic
plane near the Galactic Center, shows two high-velocity H$_2$ components at
$v_\mathrm{LSR}$ = $-79$ and $-108$ km s$^{-1}$. In contrast, the FUSE spectrum
of the nearby ($\sim$0.6$^{\circ}$ away) foreground star HD 167402 at
$d$=4.9$^{+0.8}_{-0.7}$ kpc reveals no H$_2$ absorption at these velocities.
Over 60 lines of H$_2$ from rotational levels $J$ = 0 to 5 are identified in
the high-velocity clouds. For the $v_\mathrm{LSR}$ = $-79$ km s$^{-1}$ cloud we
measure total log $N$(H$_2$) $\geq$ 16.75 cm$^{-2}$, molecular fraction
$f_\mathrm{H_2}$ $\geq$ 0.8%, and $T_{01}$ $\geq$ 97 and $T_{25}$ $\leq$ 439 K
for the ground- and excited-state rotational excitation temperatures. At
$v_\mathrm{LSR}$ = $-108$ km s$^{-1}$, we measure log $N$(H$_2$) = 16.13 $\pm$
0.10 cm$^{-2}$, $f_\mathrm{H_2}$ $\geq$ 0.5%, and $T_{01}$ = 77$^{+34}_{-18}$
and $T_{25}$ = 1092$^{+149}_{-117}$ K, for which the excited state ortho- to
para-H$_2$ is 1.0$^{+0.3}_{-0.1}$, much less than the equilibrium value of 3
expected for gas at this temperature. This non-equilibrium ratio suggests that
the $-108$ km s$^{-1}$ cloud has been recently excited and has not yet had time
to equilibrate. As the LS 4825 sight line passes close by a tilted section of
the Galactic disk, we propose that we are probing a boundary region where the
nuclear wind is removing gas from the disk.
