COMPLETING THE CENSUS OF Ly{alpha} EMITTERS AT THE REIONIZATION EPOCH

Journal Article · Mon Jun 20 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/734/2/119· OSTI ID:21576589

Kashikawa, Nobunari; Iye, Masanori ^[1]; Shimasaku, Kazuhiro; Okamura, Sadanori ^[2]; Matsuda, Yuichi ^[3]; Egami, Eiichi; Jiang, Linhua ^[4]; Nagao, Tohru; Taniguchi, Yoshiaki; Shioya, Yasuhiro ^[5]; Ouchi, Masami; Ota, Kazuaki ^[6]; Malkan, Matthew A ^[7]; Hattori, Takashi ^[8]; Ly, Chun ^[9]; Furusawa, Hisanori ^[10]; Shibuya, Takatoshi; Ishizaki, Yoshifumi; Toshikawa, Jun ^[11]

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1. Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)
2. Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan)
3. Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
4. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
5. Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)
6. Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-Ha, Kashiwa City, Chiba 77-8582 (Japan)
7. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)
8. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
9. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
10. Astronomy Data Center, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)
11. Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan)

We carried out extended spectroscopic confirmations of Ly{alpha} emitters (LAEs) at z = 6.5 and 5.7 in the Subaru Deep Field. Now, the total number of spectroscopically confirmed LAEs is 45 and 54 at z = 6.5 and 5.7, respectively, and at least 81% (70%) of our photometric candidates at z = 6.5 (5.7) have been spectroscopically identified as real LAEs. We made careful measurements of the Ly{alpha} luminosity, both photometrically and spectroscopically, to accurately determine the Ly{alpha} and rest-UV luminosity functions (LFs). The substantially improved evaluation of the Ly{alpha} LF at z = 6.5 shows an apparent deficit from z = 5.7 at least at the bright end, and a possible decline even at the faint end, though small uncertainties remain. The rest-UV LFs at z = 6.5 and 5.7 are in good agreement, at least at the bright end, in clear contrast to the differences seen in the Ly{alpha} LF. These results imply an increase in the neutral fraction of the intergalactic medium from z = 5.7 to 6.5. The rest-frame equivalent width (EW{sub 0}) distribution at z = 6.5 seems to be systematically smaller than z = 5.7, and it shows an extended tail toward larger EW{sub 0}. The bright end of the rest-UV LF can be reproduced from the observed Ly{alpha} LF and a reasonable EW{sub 0}-UV luminosity relation. Integrating this rest-UV LF provides the first measurement of the contribution of LAEs to the photon budget required for reionization. The derived UV LF suggests that the fractional contribution of LAEs to the photon budget among Lyman break galaxies significantly increases toward faint magnitudes. Low-luminosity LAEs could dominate the ionizing photon budget, though this inference depends strongly on the uncertain faint-end slope of the Ly{alpha} LF.

• OSTI ID: 21576589
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 734; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGY
GALAXIES
LUMINOSITY
LYMAN LINES
OPTICAL PROPERTIES
PHYSICAL PROPERTIES