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Deuterium abundance in the most metal-poor damped Lyman alpha system: converging on Ωb,0h^2

Pettini, Max and Zych, Berkeley J. and Murphy, Michael T. and Lewis, Antony and Steidel, Charles C. (2008) Deuterium abundance in the most metal-poor damped Lyman alpha system: converging on Ωb,0h^2. Monthly Notices of the Royal Astronomical Society, 391 (4). pp. 1499-1510. ISSN 0035-8711. doi:10.1111/j.1365-2966.2008.13921.x.

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The most metal-poor damped Lyα system known to date, at zabs= 2.61843 in the spectrum of the QSO Q0913+072, with an oxygen abundance of only ∼1/250 of the solar value, shows six well-resolved DI Lyman series transitions in high-quality echelle spectra recently obtained with the European Southern Observatory (ESO) VLT. We deduce a value of the deuterium abundance log (D/H) =−4.56 ± 0.04 which is in good agreement with four out of the six most reliable previous determinations of this ratio in QSO absorbers. We find plausible reasons why in the other two cases the 1σ errors may have been underestimated by about a factor of two. The addition of this latest data point does not significantly change the mean value of the primordial abundance of deuterium, suggesting that we are now converging to a reliable measure of this quantity. We conclude that〈log (D/H)p〉=−4.55 ± 0.03 and Ωb,0h2(BBN) = 0.0213 ± 0.0010 (68 per cent confidence limits). Including the latter as a prior in the analysis of the Wilkinson Microwave Anisotropy Probe (WMAP) five-year data leads to a revised best-fitting value of the power-law index of primordial fluctuations ns= 0.956 ± 0.013 (1σ) and ns < 0.990 with 99 per cent confidence. Considering together the constraints provided by WMAP 5, (D/H)p, baryon oscillations in the galaxy distribution, and distances to Type Ia supernovae, we arrive at the current best estimates Ωb,0h2= 0.0224 ± 0.0005 and ns= 0.959 ± 0.013.

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Pettini, Max0000-0002-5139-4359
Steidel, Charles C.0000-0002-4834-7260
Additional Information:© 2008 The Authors. Journal compilation © 2008 RAS. Accepted 2008 September 5. Received 2008 September 2; in original form 2008 May 1. Published Online: 24 November 2008. The work presented in this paper is based on UVES observations made with the ESO VLT/Kueyen telescope at Paranal, Chile, obtained in programme 078.A-0185(A) and from the public data archive. We are grateful to the ESO time assignment committee, and to the staff astronomers at VLT, for their help in conducting the observations. Bob Carswell, Jim Lewis and Sam Rix kindly helped with various aspects of the data analysis, and John O'Meara and Gary Steigman offered valuable comments on an earlier version of the paper. We also thank the anonymous referee for useful suggestions on the presentation of the data. We acknowledge the use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA). Support for LAMBDA is provided by the NASA Office of Space Science. MTM thanks the Australian Research Council for a QEII research fellowship (DP0877998). CCS's research is partly supported by grant AST-0606912 from the US National Science Foundation.
Funding AgencyGrant Number
European Southern Observatory078.A-0185(A)
Australian Research CouncilUNSPECIFIED
Subject Keywords:quasars: absorption lines; quasars: individual: Q0913+072; cosmology: observations
Issue or Number:4
Record Number:CaltechAUTHORS:PETmnras08b
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12915
Deposited By: Archive Administrator
Deposited On:13 Jan 2009 02:49
Last Modified:08 Nov 2021 22:33

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