Spitzer and hubble space telescope constraints on the physical properties of the z ∼ 7 galaxy strongly lensed by A2218

E. Egami, J. P. Kneib, G. H. Rleke, R. S. Ellis, J. Richard, J. Rigby, C. Papovich, D. Stark, M. R. Santos, J. S. Huang, H. Dole, E. Le Floc'h, P. G. Pérez-González

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

We report the detection of a z ∼ 7 galaxy strongly lensed by the massive galaxy cluster A2218 (z = 0.175) at 3.6 and 4.5 μm using the Spitzer Space Telescope and at 1.1 μm using the Hubble Space Telescope. The new data indicate a refined photometric redshift in the range of 6.6-6.8 depending on the presence of Lyα emission. The spectral energy distribution is consistent with having a significant Balmer break, suggesting that the galaxy is in the poststarburst stage with an age of at least ∼50 Myr and quite possibly a few hundred million years. This suggests the possibility that a mature stellar population is already in place at such a high redshift. Compared with typical Lyman break galaxies at z ∼ 3-4, the stellar mass is an order of magnitude smaller (∼109 M), but the specific star formation rate (star formation rate/M/star) is similarly large (>10-9yr-1), indicating equally vigorous star-forming activity.

Original languageEnglish (US)
Pages (from-to)L5-L8
JournalAstrophysical Journal
Volume618
Issue number1 II
DOIs
StatePublished - Jan 1 2005

Keywords

  • Cosmology: observations
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Egami, E., Kneib, J. P., Rleke, G. H., Ellis, R. S., Richard, J., Rigby, J., Papovich, C., Stark, D., Santos, M. R., Huang, J. S., Dole, H., Floc'h, E. L., & Pérez-González, P. G. (2005). Spitzer and hubble space telescope constraints on the physical properties of the z ∼ 7 galaxy strongly lensed by A2218. Astrophysical Journal, 618(1 II), L5-L8. https://doi.org/10.1086/427550