Emission Line Mapping of the Circumgalactic Medium of Nearby Galaxies
  The circumgalactic medium (CGM), which harbors > 50% of all the baryons in a
galaxy, is both the reservoir of gas for subsequent star formation and the
depository of chemically processed gas, energy, and angular momentum from
feedback. As such, the CGM obviously plays a critical role in galaxy evolution.
We discuss the opportunity to image this component using recombination line
emission, beginning with the early results coming from recent statistical
detection of this emission to the final goal of realizing spectral-line images
of the CGM in individual nearby galaxies. Such work will happen in the next
decade and provide new insights on the galactic baryon cycle.
