Luminous Lyman Break Galaxies atz > 5 and the Source of Reionization

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Abstract
We have discovered six galaxies with spectroscopically confirmed redshifts of 4.81.5 in the field, this photometric cut designed to select galaxies at z>4.8. The line fluxes range between 0.2 to 2.5 x 10^-17 ergs cm^-2 s^-1 indicating luminosities of around 10^42-43 ergs s^-1 for Ly-alpha and their high emission line equivalent widths suggest very young ages (~5.3 ionized. These galaxies are observed within several hundred Myr of the end of the epoch of reionization (z=6-7), with little time for the luminosity function to evolve. This, and the lack of detected quasars, imply that the bulk of the UV flux that reionized the universe came from faint galaxies with M_(1700 ang)>-21.Comment: 24 pages (latex, aas macros), 7 figures (12 postscript files), accepted for publication in the Astrophysical Main Journa