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We present a measurement of the D/H abundance ratio in a metal-poor damped Lyman alpha (DLA) system along the sightline of QSO SDSS1558-0031. The DLA system is at redshift z = 2. 70262, has a neutral column density of log (NHI) =20. 67+/-0. 05 cm², and a gas-phase metallicity O/H= -1. 49 which indicates that deuterium astration is negligible. Deuterium absorption is observed in multiple Lyman series with a column density of log (NDI) =16. 19+/-0. 04 cm², best constrained by the deuterium Lyman-11 line. We measure log (D/H) = -4. 48+/-0. 06, which when combined with previous measurements along QSO sightlines gives a best estimate of log (D/H) = -4. 55+/-0. 04, where the 1-sigma error estimate comes from a jackknife analysis of the weighted means. Using the framework of standard big bang nucleosynthesis, this value of D/H translates into a baryon density of Omegab h² = 0. 0213 +/- 0. 0013 +/- 0. 0004 where the error terms represent the 1-sigma errors from D/H and the uncertainties in the nuclear reaction rates respectively. Combining our new measurement with previous measurements of D/H, we no longer find compelling evidence for a trend of D/H with NHI.
O’Meara et al. (Wed,) studied this question.