研究成果・発表論文

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

Kashikawa, Nobunari,   Shimasaku, Kazuhiro,   Malkan, Matthew A.,   Doi, Mamoru,   Matsuda, Yuichi,   Ouchi, Masami,   Taniguchi, Yoshiaki,   Ly, Chun,   Nagao, Tohru,   Iye, Masanori,   Motohara, Kentaro,   Murayama, Takashi,   Murozono, Kouji,   Nariai, Kyoji,   Ohta, Kouji,   Okamura, Sadanori,   Sasaki, Toshiyuki,   Shioya, Yasuhiro,   & Umemura, Masayuki


要旨
We report an extensive search for Ly\ensuremathα emitters (LAEs) at z=6.5 in the Subaru Deep Field. Subsequent spectroscopy with Subaru and Keck identified eight more LAEs, giving a total of 17 spectroscopically confirmed LAEs at z=6.5. Based on this spectroscopic sample of 17, complemented by a photometric sample of 58 LAEs, we have derived a more accurate Ly\ensuremathα luminosity function of LAEs at z=6.5, which reveals an apparent deficit at the bright end of åisebox-0.5ex~0.75 mag fainter L$^*$, compared with that observed at z=5.7. The difference in the LAE luminosity functions between z=5.7 and 6.5 is significant at the 3 \ensuremathσ level, which is reduced to 2 \ensuremathσ when cosmic variance is taken into account. This result may imply that the reionization of the universe has not been completed at z=6.5. We found that the spatial distribution of LAEs at z=6.5 was homogeneous over the field. We discuss the implications of these results for the reionization of the universe.

The data presented herein were partly obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.




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