A bright lensed galaxy at z = 5.4 with strong Lyα 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


We present a detailed study of a unusually bright, lensed galaxy at z = 5.424 discovered within the CFHTLS imaging 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 Lyα emission, reaching a peak in (observed) flux density of > 1016 erg s1 cm2 Å1. A deep optical spectrum from the LBT places strong constraints on N V and C IV emission, disfavouring an AGN source for the emission. However, a detection of the N IV] λ1486 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 Lyα emission, which is marginally resolved on ∼few kpc scales and has EW0 ∼ 260Å. The Lyα emission extends over ∼ 2000 km s1 and is broadly consistent with expanding shell models. SED fitting that includes Spitzer/IRAC photometry suggests a complex star formation history that include both a recent burst and an evolved population. J1414+5446 lies 3000 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 reionization and a preview of what can be expected from upcoming wide-area surveys that will yield hundreds of similar objects.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Jun 28 2017


  • Cosmology
  • Dark ages
  • First stars – galaxies: high-redshift –
  • Galaxies: groups: individual: SL2S J141447+544703
  • Galaxies: individual: CFHTLS J141446.82+544631.9
  • Galaxies: ISM
  • Gravitational lensing: strong
  • Reionization

ASJC Scopus subject areas

  • General

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