Abstract
A new observation of D in a primordial gas cloud, made using the high-resolution spectrograph at the Keck telescope, indicates an abundance D/H = (1.9-2.5) × 10-4 (Songaila et al. 1994). Because the new measurement is substantially larger than previous, Galactic estimates, this would force a reassessment of big bang nucleosynthesis (BBN) methodology and predictions - if it is confirmed. Using a new BBN Monte Carlo code and analysis technique (Kernan & Krauss 1994), we derive constraints implied by a lower limit of D/H = 1.9 × 10-4. We find ΩB ≤ 0.0068 h-2, which is definitively incompatible with baryonic halo dark matter. We also explore implications of combining the D measurement with other light-element abundances. 7Li provides a lower bound, ΩB ≥ 0.004 h-2. Also, the initial 4He mass fraction (Yp) would have to be less than 23.5%, assuming three light neutrino species - in good agreement with present observational estimates. Finally, observational upper limits of Yp ≤ 24% and 7Li/H ≤ 2.3 × 10-10 would now allow the number of effective neutrino species to be as large as 3.9.
Original language | English (US) |
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Pages (from-to) | L79-L81 |
Journal | Astrophysical Journal |
Volume | 432 |
Issue number | 2 PART 2 |
DOIs | |
State | Published - Sep 10 1994 |
Keywords
- Cosmology: observations
- Early universe
- Nuclear reactions, nucleosynthesis, abundances
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science