Matt Kistler homepage.   Matthew Kistler  The Star Formation Rate in the Reionization Era as Indicated by Gamma-ray Bursts

Gamma-ray bursts offer an extraordinary opportunity to study aspects of the early Universe, including the cosmic star formation rate.  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, in this paper, completed with Hasan Yuksel, John Beacom, Andrew Hopkins, and Stuart Wyithe, 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 measurements based on Lyman-break galaxies 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 account for the long-standing problem of cosmic reionization.