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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Siana, Brian
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Topics
Publications (3/3 displayed)
- 2015Spectroscopic detection of C IV λ1548 in a galaxy at z = 7.045: implications for the ionizing spectra of reionization-era galaxiescitations
- 2011Very Strong Emission-line Galaxies in the WFC3 Infrared Spectroscopic Parallel Survey and Implications for High-redshift Galaxiescitations
- 2010A Spectroscopic Search for Leaking Lyman Continuum at z ~ 0.7citations
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article
Spectroscopic detection of C IV λ1548 in a galaxy at z = 7.045: implications for the ionizing spectra of reionization-era galaxies
Abstract
We present Keck/MOSFIRE observations of UV metal emission lines in four bright (H = 23.9-25.4) gravitationally lensed z ≃ 6-8 galaxies behind the cluster Abell 1703. The spectrum of A1703-zd6, a highly magnified star-forming galaxy with a Lyα redshift of z = 7.045, reveals a confident detection of the nebular C IV λ1548 emission line (unresolved with full width at half-maximum<125 km s<SUP>-1</SUP>). UV metal emission lines are not detected in the three other galaxies. At z ≃ 2-3, nebular C IV emission is observed in just 1 per cent of UV-selected galaxies. The presence of strong C IV emission in one of the small sample of galaxies targeted in this paper may indicate that hard ionizing spectra are more common at z ≃ 7. The total estimated rest-frame equivalent width of the C IV doublet and C IV/Lyα flux ratio are comparable to measurements of narrow-lined AGNs. Photoionization models show that the nebular C IV line can also be reproduced by a young stellar population, with very hot metal-poor stars dominating the photon flux responsible for triply ionizing carbon. Regardless of the origin of the C IV, we show that the ionizing spectrum of A1703-zd6 is different from that of typical galaxies at z ≃ 2, producing more H ionizing photons per unit 1500 Å luminosity (log(ξ<SUB>ion</SUB>/erg<SUP>- 1</SUP> Hz) = 25.68) and a larger flux density at 30-50 eV. If such extreme radiation fields are typical in UV-selected systems at z ≳ 7, it would indicate that reionization-era galaxies are more efficient ionizing agents than previously thought. Alternatively, we suggest that the small sample of Lyα emitters at z ≳ 7 may trace a rare population with intense radiation fields capable of ionizing their surrounding hydrogen distribution. Additional constraints on high-ionization emission lines in galaxies with and without Lyα detections will help clarify whether hard ionizing spectra are common in the reionization era....