http://arxiv.org/abs/1706.09512
The $z_{\rm abs} = 2.504$ Lyman Limit absorption system, towards the $z_{\rm em} = 2.63$ quasar Q1009+2956, has previously been used to estimate the primordial deuterium abundance. Since the initial measurement by Burles & Tytler, this quasar has been re-observed many times with the Keck telescope, providing a substantial increase in signal-to-noise (from 60 to 147 at continuum level of Ly-$\alpha$ at $z_{\rm abs}=2.504$). Several heavy element absorption lines are detected at this redshift, providing strong constraints on the kinematic structure. We explore six different models for the absorption system and find that the deuterium feature is contaminated by Ly-$\alpha$ absorption from a low column density H I cloud. This significantly limits precision to which one can estimate the D/H ratio in this LLS. Our favoured model results in a primordial value of $\log{\rm D/H}=-4.50\pm0.08$.
E. Zavarygin, J. Webb, V. Dumont, et. al.
Fri, 30 Jun 17
28/65
Comments: Submitted to MNRAS, 14 pages, 8 figures, 5 tables
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