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

September 2018 • 2018MNRAS.479..435M

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

Abstract • We present a detailed study of an unusually bright, lensed galaxy at z = 5.424 discovered within the CFHTLS imaging survey. With an observed flux of i_AB = 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^-16erg s^-1 cm^-2Å^-1. A deep optical spectrum from the Large Binocular Telescope places strong constraints on N V and C IV emission, disfavouring an Active Galactic Nucleus (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 Ly α emission, which is marginally resolved on approximately few kpc 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.

Links

• PREPRINT http://arxiv.org/abs/1706.09428
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/2018MNRAS.479..435M
• ELECTR https://doi.org/10.1093%2Fmnras%2Fsty1411
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2018MNRAS.479..435M
• PDF http://academic.oup.com/mnras/pdf-lookup/doi/10.1093/mnras/sty1411
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2018MNRAS.479..435M
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2018MNRAS.479..435M
• DATA https://irsa.ipac.caltech.edu/bibdata/2018/M/2018MNRAS.479..435M.html