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 journalArticlepeer-review

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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