Subaru First-Light Deep Photometry of Galaxies in A 851 Field
Kobayashi, Naoto; Terada, Hiroshi; Usuda, Tomonori; Imanishi, Masatoshi; Shimasaku, Kazuhiro; Simpson, Chris; Tamura, Motohide; Hayashi, Masahiko; Yoshida, Michitoshi; Nakata, Fumiaki; Okamura, Sadanori; Ando, Hiroyasu; Noguchi, Kunio; Itoh, Yoichi; Furusawa, Hisanori; Komiyama, Yutaka; Miyazaki, Satoshi; Takata, Tadafumi; Karoji, Hiroshi; Hayashi, Saeko S.; Goto, Miwa; Iye, Masanori; Nishimura, Tetsuo; Suto, Hiroshi; Takato, Naruhisa; Tomono, Daigo; Takami, Hideki; Kashikawa, Nobunari; Doi, Mamoru; Akiyama, Masayuki; Miyata, Takashi; Motohara, Kentaro; Yagi, Masafumi; Nishikawa, Jun; Kato, Taichi; Ichikawa, Takashi; Sekiguchi, Kazuhiro; Yasuda, Naoki; Omata, Koji; Iwamuro, Fumihide; Maihara, Toshinori; Yamashita, Takuya; Oya, Shin; Kaifu, Norio; Kimura, Masahiko; Aoki, Tsutomu; Ebizuka, Noboru; Inata, Motoko; Kosugi, George; Okita, Kiichi; Sasaki, Toshiyuki; Tanabe, Hirohisa; Taguchi, Tomoyuki; Hata, Ryuji; Chikada, Yoshihiro; Kobayashi, Yukiyasu; Aoki, Tetsuo; Fukuda, Takeo; Hamabe, Masaru; Horaguchi, Toshihiro; Ichikawa, Shinichi; Imi, Katsumi; Isobe, Shuzo; Iwai, Junichi; Kamata, Yukiko; Kanzawa, Tomio; Kawasaki, Wataru; Kodaira, Keiichi; Kurakami, Tomio; Mikami, Yoshitaka; Miyashita, Akihiko; Mizumoto, Yoshihiko; Nakagiri, Masao; Nakajima, Koich; Nakamura, Kyoko; Nariai, Kyoji; Nishihara, Eiji; Nishimura, Shiro; Nishino, Tetsuo; Noguchi, Takeshi; Noumaru, Junichi; Ogasawara, Ryusuke; Okada, Norio; Oshima, Norio; Otsubo, Masashi; Sasaki, Goro; Sawada, Yasuhiro; Sekiguchi, Maki; Shelton, Ian; Suzuki, Katsuyuki; Tanaka, Kyoko; Tanaka, Wataru; Torii, Yasuo; Tsukamoto, Hiroyuki; Watanabe, Junichi; Watanabe, Masaru; Yamashita, Yasumasa; Yoshida, Shigeomi; Yutani, Masami
Japan, United States
Abstract
We report on the results of optical and near-infrared photometry of the cluster of galaxies A 851 (=CL 0939+4713) carried out as one of the first-light observations of the 8.2 m Subaru telescope on Mauna Kea. Images as sharp as 0.''3 FWHM in K' and 0.''45 in R were obtained in these observations. The 3 sigma limiting magnitudes for points sources in 0.''3 seeing with a 0.''6 software aperture were shown to go down to R=28.1, J=25.1, and K'=24.0, respectively, for about 1 hour integration. Subaru photometry of the galaxies in this cluster has shown in its color-magnitude diagrams a well-defined sequence of the early-type galaxy population that is consistent with the track predicted for a single-burst passive-evolution model of galaxies at z = 0.4. We attempted a morphological classification of galaxies in the Subaru R-band image using the C_in method, and found that discrimination between ellipticals and spirals can be achieved fairly consistently with the types assigned by MORPHs on the HST F702W image down to R<23. A weak lensing analysis made on the Subaru R-band image yielded a reconstructed surface mass-density distribution that shows a significant maximum corresponding to the peak of the smoothed luminosity distribution of cluster galaxies. We found no significant excess of faint and/or small galaxies in the putative cluster area around the z=2 quasar and no difference in the colors for galaxies in this area from those in the main cluster either. Two extremely red objects (ERO) with R-K>6 are newly identified in the field. The colors of the reddest, disk-shaped galaxy R1 are found compatible with those of an unreddened E/S0 galaxy at z = 1.6.