High Deuterium Abundance in a New Quasar Absorber
Abstract
We present a new analysis of an absorption system in the spectrum of Q 0014+813, with particular attention to a single cold cloud at redshift z = 2.797957. Features are identified at this redshift corresponding to Si III, Si IV, C IV, D I, and H I, all consistent with purely thermal broadening at T ~ 19,000 K. The deuterium identification is confirmed by its narrow width and precise agreement with the silicon and carbon redshifts. The H I column is well constrained by a slightly damped profile in the blue wing of Lyα, and the D I column by its saturation, leading to a 95% confidence lower limit (D/H) > 0.7 x 10^-4^. The abundance is measured from line fits to be (D/H) = 1.9_-0.9_^+1.6^ x 10^-4^, in agreement with the high deuterium abundance previously found in the z = 3.32 system in the same quasar spectrum. This system strengthens the case for a high universal primordial deuterium abundance and low cosmic baryon density (n = 1.7 x 10^-10^, {OMEGA}_b_h^2^ = 0.006), for which Standard Big Bang Nucleosynthesis gives concordant predictions for helium-4 and lithium-7 abundances. Implications for Galactic chemical evolution and the baryonic and nonbaryonic dark matter problems are briefly discussed.
- Publication:
-
The Astronomical Journal
- Pub Date:
- June 1996
- DOI:
- 10.1086/117949
- arXiv:
- arXiv:astro-ph/9603084
- Bibcode:
- 1996AJ....111.2135R
- Keywords:
-
- EARLY UNIVERSE;
- COSMOLOGY: OBSERVATIONS;
- QUASARS: ABSORPTION LINES;
- Astrophysics
- E-Print:
- 25 pages, gzipped postscript file, submitted to Astron. J