The Cosmic Star Formation Rate from the Faintest Galaxies in the
  Unobservable Universe
  Observations of high-z galaxies and gamma-ray bursts now allow for empirical
studies during reionization. However, even deep surveys see only the brightest
galaxies at any epoch and must extrapolate to arbitrary lower limits to
estimate the total rate of star formation. We first argue that the galaxy
populations seen in LBG surveys yield a GRB rate at z > 8 that is an order of
magnitude lower than observed. We find that integrating the inferred UV
luminosity functions down to M_UV ~ -10 brings LBG- and GRB-inferred SFR
density values into agreement up to z ~ 8. GRBs, however, favor a far larger
amount of as yet unseen star formation at z > 9. We suggest that the SFR
density may only slowly decline out to z ~ 11, in accord with WMAP and Planck
reionization results, and that GRBs may be useful in measuring the scale of
this multitude of dwarf galaxies.
