Physical properties of spectroscopically confirmed galaxies at z ≥ 6. III. Stellar populations from SED modeling with secure Lyα emission and redshifts
- Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
- Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen (Denmark)
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Physics Department, University of the Western Cape, 7535 Bellville, Cape Town (South Africa)
- Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)
- Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan)
- Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan)
- Centre de Recherche Astrophysique de Lyon, Universite Lyon 1, 9 Avenue Charles Andre, F-69561 Saint Genis Laval Cedex (France)
We present a study of stellar populations in a sample of spectroscopically confirmed Lyman-break galaxies (LBGs) and Lyα emitters (LAEs) at 5.7<7. These galaxies have deep images from Subaru, the Hubble Space Telescope, and Spitzer/IRAC. We focus on 27 galaxies with IRAC detections, and characterize their stellar populations based on the multi-band data and secure redshifts. By estimating nebular emission from the observed Lyα flux, we break the strong model degeneracy between young galaxies with prominent nebular emission and older galaxies with strong Balmer breaks. The results show that our galaxies cover a wide range of ages from several to a few hundred million years (Myr), and stellar masses from ∼10{sup 8} to ∼10{sup 11} M{sub ⊙}. These galaxies can be roughly divided into two subsamples: an “old” subsample consisting of galaxies older than 100 Myr, with stellar masses higher than 10{sup 9} M{sub ⊙}, and a “young” subsample consisting of galaxies younger than ∼30 Myr, with masses ranging between ∼10{sup 8} and ∼ 3×10{sup 9} M{sub ⊙}. Both subsamples display a correlation between stellar mass and star formation rate (SFR), but with very different normalizations. The average specific SFR (sSFR) of the “old” subsample is 3–4 Gyr{sup −1}, consistent with previous studies of “normal” star-forming galaxies at z⩾6. The average sSFR of the “young” subsample is an order of magnitude higher, likely due to starburst activity. Our results also indicate little dust extinction in the majority of the galaxies, as already suggested by their steep rest-frame UV slopes. Finally, LAEs and LBGs with strong Lyα emission are indistinguishable in terms of age, stellar mass, and SFR.
- OSTI ID:
- 22882324
- Journal Information:
- Astrophysical Journal, Vol. 816, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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