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arXiv · 1702.03687

Observations of the Lyman series forest towards the redshift 7.1 quasar ULAS J1120+0641

R. Barnett·S. J. Warren·G. D. Becker·D. J. Mortlock·P. C. Hewett·R. G. McMahon·C. Simpson·B. P. Venemans
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Abstract

We present a 30h integration Very Large Telescope X-shooter spectrum of the Lyman series forest towards the $z = 7.084$ quasar ULAS J1120+0641. The only detected transmission at ${\rm S/N}>5$ is confined to seven narrow spikes in the Ly$α$ forest, over the redshift range $5.858 5.5$. The data nevertheless provide only a weak limit on the volume-weighted hydrogen intergalactic (IGM) neutral fraction at $z\sim 6.5$, $x_{\rm HI} > 10^{-4}$, similar to limits at redshift $z\sim6$ from less distant quasars. The new observations cannot extend measurements of the neutral fraction of the IGM to higher values because absorption in the Ly$α$ forest is already saturated near $z\sim6$. For higher neutral fractions, other methods such as measuring the red damping wing of the IGM will be required.

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R. Barnett, S. J. Warren, G. D. Becker, D. J. Mortlock, P. C. Hewett, R. G. McMahon, C. Simpson, B. P. Venemans. 2017-02-13. Observations of the Lyman series forest towards the redshift 7.1 quasar ULAS J1120+0641. https://doi.org/10.1051/0004-6361%2F201630258

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