Recent observations and simulations suggest that a dynamic ISM is essential to explain the ionization and emission structure of the WIM. A turbulent, fractal medium allows LyC radiation to escape H ii regions and ionize gas far from massive stars. These elements may soon allow a fully global model to solidify the link between active star formation and powering the WIM.
WHAM will soon finish the southern component of the first all-sky kinematic H survey of the Milky Way. Followup with other emission line surveys will allow us to compare physical conditions of the WIM in a variety of conditions across the whole Galaxy. WHAM will then turn its gaze farther toward the Magellanic system to explore diffuse ionization in the unique conditions provided, in particular, by the extended structures of the Bridge and Stream.
LMH and WHAM are supported by NSF award AST-0607512. WHAM was built with the help of the University of Wisconsin Graduate School, Physical Sciences Lab, and Space Astronomy Lab. Their staff and that of KPNO and CTIO have greatly contributed to the success of the project.