相关论文: Deuterium at high redshift: primordial or evolved …
Of the light elements, the primordial abundance of deuterium, (D/H)_p, provides the most sensitive diagnostic for the cosmological mass density parameter Omega_B. Recent high redshift (D/H) measurements are highly discrepant, although this…
Detections of deuterium in high redshift Lyman limit absorption systems along the line of sight to QSOs promise to reveal the primordial deuterium abundance. At present, the deuterium abundances (D/H) derived from the very few systems…
From the analysis of the near-UV spectrum of the QSO 2206-199, obtained with a long series of exposures with STIS on the HST, we deduce a value (D/H) = (1.65 +/- 0.35) x 10(-5) (1 sigma error) for the abundance of deuterium in the z(abs) =…
The theory of Big Bang nucleosynthesis, coupled with an estimate of the primordial deuterium abundance (D/H)_pr, offers insights into the baryon density of the Universe. Independently, the baryon density can be constrained during a…
We report a new detection of neutral deuterium in the sub Damped Lyman Alpha system with low metallicity [O/H]\,=\,$-2.042 \pm 0.005$ at $z_{\rm abs}=2.437$ towards QSO~J\,1444$+$2919. The hydrogen column density in this system is…
The amount of deuterium relative to hydrogen (D/H) in clouds with close to primordial abundance seen at high redshift in the spectra of distant quasars currently provides the best estimate of the baryonic density of the Universe. The first…
The current status of extragalactic deuterium abundance is discussed using two examples of `low' and `high' D/H measurements. We show that the discordance of these two types of D abundances may be a consequence of the spatial correlations…
The discordance between `low' and `high' primordial D/H measurements can be considerably reduced if the analysis of the H+D profiles accounts for the correlated velocity field of bulk motion. We have re-estimated the value of D/H at z=3.572…
The primordial abundance of deuterium (D/H) yields a measure of the density of baryons in the universe and is an important complement to determinations from cosmic microwave background (CMB) experiments. Indeed, the current small sample of…
Among the light elements created in the Big Bang, deuterium is one of the most difficult to detect but is also the one whose abundance depends most sensitively on the density of baryons. Thus, although we still have only a few positive…
Standard big bang nucleosynthesis (BBNS) promises accurate predictions of the primordial abundances of deuterium, helium-3, helium-4 and lithium-7 as a function of a single parameter. Previous measurements have nearly always been…
Galactic destruction of primordial deuterium is inevitably linked through star formation to the chemical evolution of the Galaxy. The relatively high present gas content and low metallicity suggest only modest D-destruction. In concert with…
We report the discovery and analysis of the most metal-poor damped Lyman-alpha (DLA) system currently known, which also displays the Lyman series absorption lines of neutral deuterium. The average [O/H] abundance of this system is [O/H] =…
We report the discovery of deuterium absorption in the very metal-poor ([Fe/H] = -2.88) damped Lyman-alpha system at z_abs = 3.06726 toward the QSO SDSS J1358+6522. On the basis of 13 resolved D I absorption lines and the damping wings of…
We present a new measurement of the deuterium-to-hydrogen ratio (D/H) in the Lyman limit absorption system at $z = 3.572$ towards Q1937--1009. We use an improved method to measure D/H in QSO absorption systems, which includes extra…
The metal-poor damped Lyman alpha (DLA) system at z = 3.04984 in the QSO SDSSJ1419+0829 has near-ideal properties for an accurate determination of the primordial abundance of deuterium, (D/H)_p. We have analysed a high-quality spectrum of…
We report the detection of Deuterium absorption at redshift 2.525659 towards Q1243+3047. We describe improved methods to estimate the Deuterium to Hydrogen abundance ratio (D/H) in absorption systems, including improved modeling of the…
Plausible ratios of deuterium to hydrogen D/H as a function of metallicity, time, and redshift are investigated. Guided by the heavy element abundance patterns observed locally in Galactic dwarf stars and at large redshift in quasi-stellar…
Observational constraints on the primordial deuterium-to-hydrogen ratio (D/H) can test theories of the early universe and provide constraints on models of big bang nucleosynthesis (BBN). We measure deuterium absorption in high-redshift,…
We report the measurement of the primordial D/H abundance ratio towards QSO \object. The column density of the hydrogen in the $z \simeq 2.536$ Lyman limit system is high, \lnhi $= 19.422 \pm 0.009$ \cmm, allowing for the deuterium to be…