CLASH: Three strongly lensed images of a candidate z ≈ 11 galaxy

Dan Coe, Adi Zitrin, Mauricio Carrasco, Xinwen Shu, Wei Zheng, Marc Postman, Larry Bradley, Anton Koekemoer, Rychard Bouwens, Tom Broadhurst, Anna Monna, Ole Host, Leonidas A. Moustakas, Holland Ford, John Moustakas, Arjen Van Der Wel, Megan Donahue, Steven A. Rodney, Narciso Benítez, Stephanie JouvelStella Seitz, Daniel D. Kelson, Piero Rosati

Research output: Contribution to journalArticlepeer-review

297 Scopus citations

Abstract

We present a candidate for the most distant galaxy known to date with a photometric redshift of z = 10.7+0.6-0.4 (95% confidence limits; with z < 9.5 galaxies of known types ruled out at 7.2σ). This J-dropout Lyman break galaxy, named MACS0647-JD, was discovered as part of the Cluster Lensing and Supernova survey with Hubble (CLASH). We observe three magnified images of this galaxy due to strong gravitational lensing by the galaxy cluster MACSJ0647.7+7015 at z = 0.591. The images are magnified by factors of ∼80, 7, and 2, with the brighter two observed at ∼26th magnitude AB (∼0.15 μJy) in the WFC3/IR F160W filter (∼1.4-1.7 μm) where they are detected at ≳12σ. All three images are also confidently detected at ≳6σ in F140W (∼1.2-1.6 μm), dropping out of detection from 15 lower wavelength Hubble Space Telescope filters (∼0.2-1.4 μm), and lacking bright detections in Spitzer/IRAC 3.6 μm and 4.5 μm imaging (∼3.2-5.0 μm). We rule out a broad range of possible lower redshift interlopers, including some previously published as high-redshift candidates. Our high-redshift conclusion is more conservative than if we had neglected a Bayesian photometric redshift prior. Given CLASH observations of 17 high-mass clusters to date, our discoveries of MACS0647-JD at z ∼ 10.8 and MACS1149-JD at z ∼ 9.6 are consistent with a lensed luminosity function extrapolated from lower redshifts. This would suggest that low-luminosity galaxies could have reionized the universe. However, given the significant uncertainties based on only two galaxies, we cannot yet rule out the sharp drop-off in number counts at z ≳ 10 suggested by field searches.

Original languageEnglish
Article number32
JournalAstrophysical Journal
Volume762
Issue number1
DOIs
StatePublished - 1 Jan 2013
Externally publishedYes

Keywords

  • early universe
  • galaxies: distances and redshifts
  • galaxies: evolution
  • galaxies: high-redshift
  • gravitational lensing: strong

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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