In Situ Probes of the First Galaxies and Reionization: Gamma-ray Bursts
  The first structures in the Universe formed at z>7, at higher redshift than
all currently known galaxies. Since GRBs are brighter than other cosmological
sources at high redshift and exhibit simple power-law afterglow spectra that is
ideal for absorption studies, they serve as powerful tools for studying the
early universe. New facilities planned for the coming decade will be able to
obtain a large sample of high-redshift GRBs. Such a sample would constrain the
nature of the first stars, galaxies, and the reionization history of the
Universe.
