The End of the Reionization Epoch Probed by Ly-alpha Emitters at z=6.5 in the Subaru Deep Field

We report an extensive search for Lyman-alpha emitters (LAEs) at z=6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru/Keck identified eight more LAEs, giving us a total of 17 spectroscopically confirmed LAEs at z=6.5. Based on these 17 spectroscopic sample complemented by the 58 photometric sample, we derived a more accurate Ly-alpha luminosity function of LAEs at z=6.5, that reveals an apparent deficit at the bright end, of ~0.75 mag fainter L*, compared with that of z=5.7. The difference of LAE luminosity functions between z=5.7 and z=6.5 has a 3-sigma significance, which is reduced to 2-sigma when taking into account the cosmic variance. This result could be an implication that the reionization of the universe has not been completed at z=6.5. The spatial distribution of LAEs at z=6.5 was found to be homogeneous over the field. We discuss some implications to the reionization of the universe