  The next generation of astronomical instruments will be able to detect dense
pockets of ionized gas created by the first luminous objects. The integrated
free-free emission from ionized halos creates a spectral distortion of the
Cosmic Microwave Background, greater than the distortion due to the reionized
intergalactic medium. Its detection is well within the capabilities of the
planned DIMES satellite. Ionized halos may also be imaged directly in free-free
emission by the Square Kilometer Array. Bright halos will be detected as
discrete sources, while residual unresolved sources can still be detected
statistically from temperature fluctuations in maps. Balmer line emission from
ionized halos is detectable by the Next Generation Space Telescope and can be
used to obtain redshift information. Unlike Ly-alpha, the H-alpha line does not
suffer from resonant scattering by neutral hydrogen, and is still observable
when the IGM is not fully reionized. In addition, it is less susceptible to
dust extinction. Finally, the kinetic Sunyaev-Zeldovich effect may be used to
detect ionized gas at high redshift. Used in concert, these observations will
probe ionizing emissivity, gas clumping, and star formation in the early
universe.
