Journal Article

Stellar populations of Lyα emitters at <i>z</i>= 3–4 based on deep large area surveys in the Subaru-SXDS/UKIDSS-UDS Field

Yoshiaki Ono, Masami Ouchi, Kazuhiro Shimasaku, Masayuki Akiyama, James Dunlop, Duncan Farrah, Janice C. Lee, Ross McLure, Sadanori Okamura and Makiko Yoshida

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 402, issue 3, pages 1580-1598
Published in print March 2010 | ISSN: 0035-8711
Published online February 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.16034.x
Stellar populations of Lyα emitters at z= 3–4 based on deep large area surveys in the Subaru-SXDS/UKIDSS-UDS Field

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We investigate the stellar populations of Lyα emitters (LAEs) at z= 3.1 and 3.7 in 0.65 deg2 of the Subaru/XMM–Newton Deep Field, based on rest-frame ultraviolet-to-optical photometry obtained from the Subaru/XMM–Newton Deep Survey, the UKIRT Infrared Deep Sky Survey/Ultra Deep Survey (UKIDSS/UDS), and the Spitzer legacy survey of the UKIDSS/UDS. Among a total of 302 LAEs (224 for z= 3.1 and 78 for z= 3.7), only 11 are detected in the K band, i.e. brighter than K(3σ) = 24.1 mag. Eight of the 11 K-detected LAEs are spectroscopically confirmed. In our stellar population analysis, we treat K-detected objects individually, while K-undetected objects are stacked at each redshift. We find that the K-undetected objects, which should closely represent the LAE population as a whole, have low stellar masses of ∼108–108.5 M, modest star formation rates (SFRs) of 1–100 M yr−1, and modest dust extinction of E(BV) < 0.2. The K-detected objects are massive, Mstar∼ 109–1010.5 M, and have significant dust extinction with a median of E(BV)≃ 0.3. Four K-detected objects with the reddest spectral energy distributions, two of which are spectroscopically confirmed, are heavily obscured with E(BV)∼ 0.65, and their continua resemble those of some local ultraluminous infrared galaxies (ULIRGs). Interestingly, they have large Lyα equivalent widths ≃70–250 Å. If these four are excluded, our sample has a weak anticorrelation between Lyα equivalent width and Mstar. We compare the stellar masses and the specific SFRs (sSFRs) of LAEs with those of Lyman-break galaxies (LBGs), distant red galaxies, submillimetre galaxies, and I- or K-selected galaxies with photometric redshifts of zphot∼ 3. We find that the LAE population is the least massive among all the galaxy populations in question, but with relatively high sSFRs, while near-infrared (NIR)-detected LAEs have Mstar and sSFR similar to LBGs. Our reddest four LAEs have very high sSFRs in spite of large Mstar, thus occupying a unique region in the Mstar versus sSFR space.

Keywords: galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: stellar content; cosmology: observations

Journal Article.  12750 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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