A Strong Ly\ensuremathα Emitter at z = 6.33 in the Subaru Deep Field Selected as an i'-Dropout
Nagao, T., Taniguchi, Y., Kashikawa, N., Kodaira, K., Kaifu, N., Ando, H., Karoji, H., Ajiki, M., Akiyama, M., Aoki, K., Doi, M., Fujita, S.~S., Furusawa, H., Hayashino, T., Iwamuro, F., Iye, M., Kobayashi, N., Kodama, T., Komiyama, Y., Matsuda, Y., Miyazaki, S., Mizumoto, Y., Morokuma, T., Motohara, K., Murayama, T., Nariai, K., Ohta, K., Okamura, S., Ouchi, M., Sasaki, T., Sato, Y., Sekiguchi, K., Shimasaku, K., Shioya, Y., Tamura, H., Tanaka, I., Umemura, M., Yamada, T., Yasuda, N., & Yoshida, M.
We report on the discovery of a star-forming galaxy at z=6.33 in the Subaru Deep Field. This object is selected as a candidate of an i$^′$-dropout high-redshift galaxy around z=6 because of its red i$^′$-z$^′$ color in our deep optical imaging survey in the Subaru Deep Field. Our follow-up optical spectroscopy reveals that this object is a strong Ly\ensuremathα emitter with only very faint ultraviolet continuum. The rest- frame equivalent width of the detected Ly\ensuremathα emission is as much as 130 ̊A. Thus the light detected in our z$^′$ image is largely attributed to the Ly\ensuremathα emission, i.e., \i̊sebox-0.5ex~40% of the z$^′$-band flux is the strong Ly\ensuremathα emission, giving a very red i$^′$-z$^′$ color. This is consistent with the photometric property of this object because the narrowband data obtained with the NB921 filter show a significant depression, z$^′$-NB921=-0.54 mag. By using the photometric data, we show that some other objects among the 48 i$^′$-dropout high- redshift galaxy candidates found in the Subaru Deep Field also show a significant NB921 depression. We briefly discuss the nature of these NB921-depressed objects. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.