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تسجيل مستخدم جديدThe primordial deuterium abundance : problems and prospects
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The current status of extragalactic deuterium abundance is discussed using two examples of `low and `high D/H measurements. We show that the discordance of these two types of D abundances may be a consequence of the spatial correlations in the stochastic velocity field. Within the framework of the generalized procedure (accounting for such effects) one finds good agreement between different observations and the theoretical predictions for standard big bang nucleosynthesis (SBBN). In particular, we show that the deuterium absorption seen at z = 2.504 toward Q1009+2956 and the H+D Ly-alpha profile observed at z = 0.701 toward Q1718+4807 are compatible with D/H $sim 4.1 - 4.6times10^{-5}$. This result supports SBBN and, thus, no inhomogeneity is needed. The problem of precise D/H measurements is discussed.
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Deuterium abundances measured recently from QSO absorption-line systems lie in the range from 3 10^{-5} to 3 10^{-4}, which shed some questions on standard big bang theory. We show that this discordance may simply be an artifact caused by inadequate
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