A bright lensed galaxy at $z=5.4$ with strong Ly$\alpha$ emission

Abstract

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 $i_{\mathrm{AB}}=23.0$, J141446.82+544631.9 is one of the brightest galaxies known at $z>5$. It is characterized by strong Ly$\alpha$ emission, reaching a peak in (observed) flux density of $>10^{-16}\mathrm{erg}{\mathrm{s}}^{-1}{\mathrm{cm}}^{-2}{\mathring{\mathrm{A}}}^{-1}$. A deep optical spectrum from the LBT places strong constraints on NV and CIV emission, disfavouring an AGN source for the emission. However, a detection of the NIV]~$\lambda$1486 emission line indicates a hard ionizing continuum, possibly from hot, massive stars. Resolved imaging from HST deblends the galaxy from a foreground interloper; these observations include narrowband imaging of the Ly$\alpha$ emission, which is marginally resolved on $\sim$few~kpc scales and has EW${}_0\sim$ 260Å. The Ly$\alpha$ emission extends over ~2000~$\mathrm{km}{\mathrm{s}}^{-1}$ 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 30" 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 $5\le \mu \le 25$. 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.

19 pages, 13 figures, accepted for publication in MNRAS

References in corpus (10)

• UV Luminosity Functions at redshifts z~4 to z~10: 10000 Galaxies from HST Legacy Fields
• Cosmic Reionization and Early Star-Forming Galaxies: A Joint Analysis of New Constraints from Planck and Hubble Space Telescope
• A Bayesian approach to strong lensing modelling of galaxy clusters
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• Spectroscopic detections of CIII]1909 at z~6-7: A new probe of early star forming galaxies and cosmic reionisation
• Ly$\alpha$ profile, dust, and prediction of Ly$\alpha$ escape fraction in Green Pea Galaxies
• The Impact of The IGM on High-Redshift Lyman Alpha Emission Lines
• Gravitationally Lensed Galaxies at 2<z<3.5: Direct Abundance Measurements of Lya Emitters
• Evidence for a Hard Ionizing Spectrum from a z=6.11 Stellar Population
• The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS

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• The Faint End of the z=5 Quasar Luminosity Function from the CFHTLS
• Spectroscopic Constraints on UV Metal Line Emission at z~6-9: The Nature of Lyman-alpha Emitting Galaxies in the Reionization-Era
• Modeling $237$ Lyman-$\alpha$ spectra of the MUSE-Wide survey
• On the nature and physical conditions of the luminous Lya emitter CR7 and its rest-frame UV components
• The use of convolutional neural networks for modelling large optically-selected strong galaxy-lens samples
• Strong lens modelling: comparing and combining Bayesian neural networks and parametric profile fitting
• Aligned metal absorbers and the ultraviolet background at the end of reionization
• On the detectability of strong lensing in near-infrared surveys
• OV] $\lambda \lambda$1213.8,1218.3 emission from extended nebulae around quasars: contamination of Ly$\alpha$ and a new diagnostic for AGN activity in Ly$\alpha$-emitters
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XIV. A Candidate Type-II Quasar at z=6.1292