We present observations of extended, 20-kpc scale soft X-ray gas around a
luminous obscured quasar hosted by an ultra-luminous infrared galaxy caught in
the midst of a major merger. The extended X-ray emission is well fit as a
thermal gas with a temperature of kT ~ 280 eV and a luminosity of L_X ~ 10^42
erg/s and is spatially coincident with a known ionized gas outflow. Based on
the X-ray luminosity, a factor of ~10 fainter than the [OIII] emission, we
conclude that the X-ray emission is either dominated by photoionization, or by
shocked emission from cloud surfaces in a hot quasar-driven wind.Comment: Accepted for publication in ApJ, 6 pages, 2 figure