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29 March 2024
 
  » arxiv » astro-ph/0011179

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The Deuterium to Hydrogen Abundance Ratio Towards a Fourth QSO: HS0105+1619
John M. O’Meara ; David Tytler ; David Kirkman ; Nao Suzuki ; Jason X. Prochaska ; Dan Lubin ; Arthur M. Wolfe ;
Date 9 Nov 2000
Journal Astrophys.J. 552 (2001) 718-730
Subject astro-ph
AbstractWe report the measurement of the primordial D/H abundance ratio towards QSO object. The column density of the hydrogen in the $z simeq 2.536$ Lyman limit system is high, lnhi $= 19.422 pm 0.009$ cmm, allowing for the deuterium to be seen in 5 Lyman series transitions. The measured value of the D/H ratio towards QSO object is found to be D/H$ = 2.54 pm 0.23 imes 10^{-5}$. The metallicity of the system showing D/H is found to be $simeq 0.01$ solar, indicating that the measured D/H is the primordial D/H within the measurement errors. The gas which shows D/H is neutral, unlike previous D/H systems which were more highly ionized. Thus, the determination of the D/H ratio becomes more secure since we are measuring it in different astrophysical environments, but the error is larger because we now see more dispersion between measurements. Combined with prior measurements of D/H, the best D/H ratio is now D/H$ = 3.0 pm 0.4 imes 10^{-5}$, which is 10% lower than the previous value. The new values for the baryon to photon ratio, and baryonic matter density derived from D/H are $eta = 5.6 pm 0.5 imes 10^{-10} $ and ob $=0.0205 pm 0.0018$ respectively.
Source arXiv, astro-ph/0011179
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