The Star Formation Rate in the Reionization Era as Indicated by
  Gamma-ray Bursts
  High-redshift gamma-ray bursts (GRBs) offer an extraordinary opportunity to
study aspects of the early Universe, including the cosmic star formation rate
(SFR). Motivated by the two recent highest-z GRBs, GRB 080913 at z = 6.7 and
GRB 090423 at z = 8.1, and more than four years of Swift observations, we first
confirm that the GRB rate does not trace the SFR in an unbiased way. Correcting
for this, we find that the implied SFR to beyond z = 8 is consistent with
LBG-based measurements after accounting for unseen galaxies at the faint end of
the UV luminosity function. We show that this provides support for the
integrated star formation in the range 6 < z < 8 to have been alone sufficient
to reionize the Universe.
