A bright-lensed galaxy at z = 5.4 with strong Ly α emission

Ian D. McGreer, Benjamin Clément, Ramesh Mainali, Daniel P. Stark, Max Gronke, Mark Dijkstra, Xiaohui Fan, Fuyan Bian, Brenda Frye, Linhua Jiang, Jean Paul Kneib, Marceau Limousin, Gregory Walth

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


We present a detailed study of an unusually bright, lensed galaxy at z=5.424 discoveredwithin theCFHTLSimaging survey.With an observed flux of iAB =23.0, J141446.82+544631.9 is one of the brightest galaxies known at z > 5. It is characterized by strong Ly α emission, reaching a peak in (observed) flux density of > 10-16 erg s-1 cm-2Å-1. A deep optical spectrum from the Large Binocular Telescope places strong constraints on NV and C IV emission, disfavouring an Active Galactic Nucleus (AGN) source for the emission. However, a detection of the NIV] λ 1486 emission line indicates a hard ionizing continuum, possibly from hot, massive stars. Resolved imaging from HST deblends the galaxy from a foreground interloper; these observations include narrowband imaging of the Ly α emission, which is marginally resolved on approximately fewkpc scales and has EW0 ~ 260 Å. The Ly α emission extends over ~ 2000 km s-1 and is broadly consistent with expanding shell models. Spectral energy distribution fitting that includes Spitzer/IRAC photometry suggests a complex star formation history that includes both a recent burst and an evolved population. J1414+5446 lies 30 arcsec from the centre of a known lensing cluster in the CFHTLS; combined with the foreground contribution, this leads to a highly uncertain estimate for the lensing magnification in the range 5 ≲ μ ≲ 25. Because of its unusual brightness, J1414+5446 affords unique opportunities for detailed study of an individual galaxy near the epoch of re-ionization and a preview of what can be expected from upcoming wide-area surveys that will yield hundreds of similar objects.

Original languageEnglish (US)
Pages (from-to)435-453
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Sep 1 2018


  • (Cosmology:) dark ages, re-ionization, first stars
  • Galaxies: ISM-galaxies: groups: individual: SL2S J141447+544703
  • Galaxies: high-redshift
  • Galaxies: individual: CFHTLS J141446.82+544631.9
  • Gravitational lensing: strong.

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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