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

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3 Scopus citations

Abstract

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
Volume479
Issue number1
DOIs
StatePublished - Sep 1 2018

Keywords

  • (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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    McGreer, I. D., Clément, B., Mainali, R., Stark, D. P., Gronke, M., Dijkstra, M., Fan, X., Bian, F., Frye, B., Jiang, L., Kneib, J. P., Limousin, M., & Walth, G. (2018). A bright-lensed galaxy at z = 5.4 with strong Ly α emission. Monthly Notices of the Royal Astronomical Society, 479(1), 435-453. https://doi.org/10.1093/mnras/sty1411