Previous
abstract 
Next abstract
The Bregman, Kelson, and Ashe (1993) model of the Galactic HI topology can be used to predict structure in the soft x-ray background (SXRB) on scales observable by ROSAT. The model consists of hot ($10^6$K) and warm ($10^4$K) bubbles of gas imbedded in a cold neutral substrate. The hot bubbles are likened to superbubbles filled with a thermal plasma which contribute to the SXRB. By including an isotropic extragalactic background spectrum, Galactic stellar populations, and assumed bubble size and temperature distributions in the disk, we simulate a $10\deg \times 10\deg$ region of sky centered at $ l = 209\deg $ and $b = 0\deg$. When varying the filling factors of hot and warm gas, we find little overall change in the typical scales of the image structures. Typical structures visible in the C band maps are large lobes and shadowing structures with most of the flux originating from the local bubble. In the M and I bands, we find that $1\deg$ to $3\deg$ structures dominate the images. Prominent x-ray features correlate well with inverse features in the simulated 21 cm moderate-to-high velocity channel maps; bright x-ray knots correlate well with HI holes and dark x-ray patches correlate well with HI knots. We also find that the SXRB intensity decreases for $b \approx 0\deg $ in the I band images. The M band maps show the same feature if the hot gas filling factor is lower than roughly 50\%. Future ROSAT M and I band maps in the plane should provide a useful constraint on the hot gas volume filling factor as well as on other features of the model.
