Lyα emitters at z = 5.7 in the subaru deep field

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

Research output: Contribution to journalArticlepeer-review

245 Citations (Scopus)

Abstract

We present the properties of Lyα emitters (LAEs) at z = 5.7 in the Subaru Deep Field. A photometric sample of 89 LAE candidates was constructed from narrow-band data down to NB816 = 26.0 (AB) in a continuous 725 arcmin 2 area. Spectra of 39 objects satisfying the photometric selection criteria for LAEs were obtained with Subaru and Keck II Telescopes, among which 28 were confirmed LAEs, one was a nearby galaxy, and eight were unclassified. We also obtained spectra of another 24 NB816-excess objects in the field, identifying six additional LAEs. We find that the Lyα luminosity function derived from the photometric sample is reproduced well by a Schechter function with L* = 7.9-2.2+3.0 × 1042 erg s-1 and φ* = 6.3-2.0+3.0 × 10-4 Mpc-3 for α = -1.5 (fixed) over the whole luminosity range of L ≃ 3 × 1042-3 × 1043 erg s-1. We then measured the rest-frame Lyα equivalent widths for the confirmed LAEs, to find that the median among the 28 objects satisfying the photometric selection criteria is W0i = 233 Å. We infer that 30%-40% of LAEs at z = 5.7 exceed W0i = 240 Å. These large-EW objects probably cannot be accounted for by ordinary star-forming populations with a Salpeter IMF. We also find that LAEs with fainter far-UV luminosities have larger EWs. Finally, we derived the far-UV luminosity function of LAEs down to MUV ≃ -19.6 using the photometric sample, and compared it with that of Lyman-break galaxies (LBGs). We find that as high as about 80% of LBGs at z ∼ 6 have W0 i ≥ 100 Å, in sharp contrast to lower-z counterparts.

Original languageEnglish
Pages (from-to)313-334
Number of pages22
JournalPublications of the Astronomical Society of Japan
Volume58
Issue number2
DOIs
Publication statusPublished - 2006

Keywords

  • Galaxies: evolution
  • Galaxies: high-redshift
  • Galaxies: luminosity function, mass function
  • Galaxies: photometry

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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