Prospects for Probing Feedback from the First Black Holes and Stars
  During Reionization
  The feasibility of making highly redshifted HI 21-cm (rest frame)
measurements from an early epoch of the Universe between the Dark Ages and
Reionization (i.e., z>6 and nu<200 MHz) to probe the effects of feedback from
the first stars and quasars is assessed in this paper. It may be possible to
determine the distribution of hydrogen through the Universe and to constrain
the birth of the first stars and black holes via HI tomography. Such
observations may also place limits on the properties of Inflation and any
exotic heating mechanisms before the first star formation begins (e.g., dark
matter decay). The global (all-sky) HI signal after Recombination has distinct
features at different frequencies between 30 and 200 MHz that changes as the
relative balance between the CMB and spin temperatures changes due to the
expansion of the Universe and the ignition of stars and/or black holes. A
technology roadmap to approach these observations beginning with ground-based
arrays and ending with a low frequency radio array on the lunar farside is
described.
