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arXiv · 1903.06186

A metal-poor damped Ly-alpha system at redshift 6.4

Eduardo Banados·Michael Rauch·Roberto Decarli·Emanuele P. Farina·Chiara Mazzucchelli·Bram P. Venemans·Fabian Walter·Robert A. Simcoe·J. Xavier Prochaska·Thomas Cooper·Frederick B. Davies·Shi-Fan S. Chen
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Abstract

We identify a strong Ly-alpha damping wing profile in the spectrum of the quasar P183+05 at z=6.4386. Given the detection of several narrow metal absorption lines at z=6.40392, the most likely explanation for the absorption profile is that it is due to a damped Ly-alpha system. However, in order to match the data a contribution of an intergalactic medium 5-38% neutral or additional weaker absorbers near the quasar is also required. The absorption system presented here is the most distant damped Ly-alpha system currently known. We estimate an HI column density ($10^{20.68\pm0.25}\,$cm$^{-2}$), metallicity ([O/H]$=-2.92\pm 0.32$), and relative chemical abundances of a system consistent with a low-mass galaxy during the first Gyr of the universe. This object is among the most metal-poor damped Ly-alpha systems known and, even though it is observed only ~850 Myr after the big bang, its relative abundances do not show signatures of chemical enrichment by Population III stars.

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Eduardo Banados, Michael Rauch, Roberto Decarli, Emanuele P. Farina, Chiara Mazzucchelli, Bram P. Venemans, Fabian Walter, Robert A. Simcoe, J. Xavier Prochaska, Thomas Cooper, Frederick B. Davies, Shi-Fan S. Chen. 2020-03-18. A metal-poor damped Ly-alpha system at redshift 6.4. https://doi.org/10.3847/1538-4357%2Fab4129

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