A Metal-poor Damped Lyα System at Redshift 6.4

• Published in: The Astrophysical journal Vol. 885; no. 1; p. 59
• Main Authors: Bañados, Eduardo, Rauch, Michael, Decarli, Roberto, Farina, Emanuele P., Hennawi, Joseph F., Mazzucchelli, Chiara, Venemans, Bram P., Walter, Fabian, Simcoe, Robert A., Prochaska, J. Xavier, Cooper, Thomas, Davies, Frederick B., Chen, Shi-Fan S.
• Format: Journal Article
• Language: English
• Published: Philadelphia IOP Publishing 01.11.2019
• Subjects: Absorption; Abundance; Astrophysics; Big bang cosmology; Damping; Galaxies; Intergalactic media; Metallicity; Organic chemistry; Population III stars; Quasars; Red shift; Wing profiles
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab4129

Abstract We identify a strong Ly α 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 α 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 α system currently known. We estimate an H i column density of 10 20.68±0.25 cm −2 , metallicity [O/H] = −2.92 ± 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 α 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.