Spectroscopic Studies of z~5.7 and z~6.5 Galaxies: Implications for   Reionization
  The recent development of large, complete samples which identify high-redshift galaxies at z~5.7 and z~6.5 from deep, wide-field surveys provides detailed information on the earliest galaxies, their numbers, spatial and kinematic distributions, and implications for early reionization of the IGM. In this contribution we present results of spectroscopic studies of z~5.7 and z~6.5 galaxies identified from our deep, Lyman alpha narrowband and multicolor surveys conducted with the SuprimeCam mosaic CCD camera on the 8.3-m Subaru telescope and observed with the DEIMOS multi-object spectrograph on Keck. The luminosity function of the z~6.5 galaxies is shown to be similar to the luminosity function of the z~5.7 galaxy samples, suggesting that a substantial star-forming population is already in place at z~6.5. Comparisons of both individual and stacked spectra of galaxies in these two samples show that the Lyman alpha emission profiles, equivalent widths, and continuum break strengths do not substantially change over this redshift interval. The wide-field nature of the surveys also permits mapping the large-scale distribution of the high-redshift galaxies in spatial structures extending across individual SuprimeCam fields (~60 Mpc). Field-to-field variations in the number of objects at z~6.5 may shortly be able to place constraints on the porosity of the reionization boundary. 
Esther M. Hu (1), Lennox L. Cowie (1), Peter Capak (1,2), and Yuko   Kakazu (1) ((1) IfA, Univ. of Hawaii, (2) Presently at ...