The Deuterium Abundance Towards Q1937-1009
Abstract
We present a new measurement of the deuterium-to-hydrogen ratio (D/H) in the Lyman limit absorption system at towards Q1937--1009. We use an improved method to measure D/H in QSO absorption systems, which includes extra parameters to treat the continuum uncertainties, a variety of new absorption models which allow for undetected velocity structure, and the improved measurement of the total hydrogen column density by Burles & Tytler (1997a). We find that all models, including contamination, give an upper limit D/H (95 % confidence). Both this and previous analyses find contamination to be unlikely in this absorption system, A analysis in models without contamination gives D/H (67% confidence), which is higher but consistent with the earlier results of Tytler et al. (1996), and a second measurement of D/H towards Q1009+2956 (Burles & Tytler 1997). With calculations of standard big bang nucleosynthesis (SBBN) and the assumption that this measurement of D/H is representative of the primordial value, we find a high baryon-to-photon ratio, . This is consistent with primordial abundance determinations of He in H II regions (Izotov et al. 1997) and Li in the atmospheres of warm metal-poor population II stars (Bonifacio & Molaro 1997). We find a high value for the present-day baryon density, , which is consistent with other inventories of baryonic matter, from low to high redshift: clusters of galaxies, the Lyman alpha forest & the Cosmic Microwave Background.
Cite
@article{arxiv.astro-ph/9712108,
title = {The Deuterium Abundance Towards Q1937-1009},
author = {Scott Burles and David Tytler},
journal= {arXiv preprint arXiv:astro-ph/9712108},
year = {2009}
}
Comments
49 pages, 19 figures, to appear in the Astrophysical Journal