One Percent Determination of the Primordial Deuterium Abundance

• Published in: The Astrophysical journal 2018-03, Vol.855 (2), p.102
• Main Authors: Cooke, Ryan J., Pettini, Max, Steidel, Charles C.
• Format: Article
• Language: English
• Subjects: Absorption; Abundance; Astrophysics; Big bang cosmology; Cosmic microwave background; Deuterium; Metallicity; Nuclear fusion; Nuclear physics; Nuclei (nuclear physics); Oxygen; Quasars; Red shift
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aaab53

We report a reanalysis of a near-pristine absorption system, located at a redshift toward the quasar Q1243+307, based on the combination of archival and new data obtained with the HIRES echelle spectrograph on the Keck telescope. This absorption system, which has an oxygen abundance [O/H] = −2.769 ± 0.028 (≃1/600 of the solar abundance), is among the lowest metallicity systems currently known where a precise measurement of the deuterium abundance is afforded. Our detailed analysis of this system concludes, on the basis of eight D i absorption lines, that the deuterium abundance of this gas cloud is , which is in very good agreement with the results previously reported by Kirkman et al., but with an improvement on the precision of this single measurement by a factor of ∼3.5. Combining this new estimate with our previous sample of six high precision and homogeneously analyzed D/H measurements, we deduce that the primordial deuterium abundance is or, expressed as a linear quantity, this value corresponds to a one percent determination of the primordial deuterium abundance. Combining our result with a big bang nucleosynthesis (BBN) calculation that uses the latest nuclear physics input, we find that the baryon density derived from BBN agrees to within 2 σ of the latest results from the Planck cosmic microwave background data.