Precision measures of the primordial abundance of deuterium

Journal Article · Mon Jan 20 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/781/1/31· OSTI ID:22348169

Cooke, Ryan J. ^[1]; Pettini, Max ^[2]; Jorgenson, Regina A. ^[3]; Murphy, Michael T. ^[4]

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1. Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
2. Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
3. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
4. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

We report the discovery of deuterium absorption in the very metal-poor ([Fe/H] = –2.88) damped Lyα system at z {sub abs} = 3.06726 toward the QSO SDSS J1358+6522. On the basis of 13 resolved D I absorption lines and the damping wings of the H I Lyα transition, we have obtained a new, precise measure of the primordial abundance of deuterium. Furthermore, to bolster the present statistics of precision D/H measures, we have reanalyzed all of the known deuterium absorption-line systems that satisfy a set of strict criteria. We have adopted a blind analysis strategy (to remove human bias) and developed a software package that is specifically designed for precision D/H abundance measurements. For this reanalyzed sample of systems, we obtain a weighted mean of (D/H){sub p} = (2.53 ± 0.04) × 10{sup –5}, corresponding to a universal baryon density 100 Ω{sub b,} {sub 0} h {sup 2} = 2.202 ± 0.046 for the standard model of big bang nucleosynthesis (BBN). By combining our measure of (D/H){sub p} with observations of the cosmic microwave background (CMB), we derive the effective number of light fermion species, N {sub eff} = 3.28 ± 0.28. We therefore rule out the existence of an additional (sterile) neutrino (i.e., N {sub eff} = 4.046) at 99.3% confidence (2.7σ), provided that the values of N {sub eff} and of the baryon-to-photon ratio (η{sub 10}) did not change between BBN and recombination. We also place a strong bound on the neutrino degeneracy parameter, independent of the {sup 4}He primordial mass fraction, Y {sub P}: ξ{sub D} = +0.05 ± 0.13 based only on the CMB+(D/H){sub p} observations. Combining this value of ξ{sub D} with the current best literature measure of Y {sub P}, we find a 2σ upper bound on the neutrino degeneracy parameter, |ξ| ≤ +0.062.

• OSTI ID: 22348169
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 781; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ABUNDANCE
ACCURACY
BARYONS
COSMOLOGY
DAMPING
DATA
DENSITY
DESIGN
DEUTERIUM
HELIUM 4
MASS
METALS
NEUTRINOS
NUCLEOSYNTHESIS
QUASARS
RECOMBINATION
RELICT RADIATION
STANDARD MODEL
VISIBLE RADIATION