Is there deuterium in the Formula Complex in the Spectrum of Formula?

Carswell, R. F.; Rauch, Michael; Weymann, R. J.; Cooke, Andrew; Webb, John R.

doi:10.1093/mnras/268.1.l1

Cited by 188 publications

(163 citation statements)

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“…A probable measurement of a high abundance ratio was reported in one QAS: D/H ≈ 24 × 10 −5 (7,8). Here we report a measurement of low D/H = 2.3 ×10 −5 , in another QAS, which is consistent with D/H in the ISM, with models of Galactic chemical evolution, (9,10), and with earlier data (7,8) provided that D line is strongly contaminated. We have internal consistency checks, and believe that this is the first direct measurement of a primordial abundance ratio.…”

supporting

confidence: 89%

“…This last point applies only to this data, and to this QAS, which is much better constrained than all other QAS, including those with possible high D/H. Data on other absorption systems (7,8,18,19) are about 10 times less sensitive because of lower H I columns or lower quality spectra, and probably would not show D/H ≪ 10 −4 . There exist spectra of 50 -100 QSOs which have the sensitivity to detect D/H ≃ 10 −4 , and perhaps one in 10 QSOs has an absorption system which appears suitable, so we expect a few false coincidences where an H line lies at the expected position of D. These cases will give high upper limits on D/H because the N(H) values are too low to give the sensitivity needed to see low D/H.…”

mentioning

confidence: 93%

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Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Tytler

Fan

Burles

1996

Nature

305

281

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The primordial ratio of the number of deuterium to hydrogen nuclei (D/H) created in big bang nucleosynthesis is the most sensitive measure of the cosmological baryon to photon ratio and the cosmological density of baryons Ω b (1-5). In the interstellar medium (ISM) of our Galaxy D/H = 1.6 ± 0.1 × 10 −5 (6), which places a strict lower limit on the primordial abundance, because stars reduce the proportion of D in the ISM. Quasar absorption systems (QAS) should give definitive measurements of the primordial D because they can sample metal-poor gas at early epochs where the destruction of D should be negligible. A probable measurement of a high abundance ratio was reported in one QAS: D/H ≈ 24 × 10 −5 (7,8). Here we report a measurement of low D/H = 2.3 ×10 −5 , in another QAS, which is consistent with D/H in the ISM, with models of Galactic chemical evolution, (9,10), and with earlier data (7,8) provided that D line is strongly contaminated. We have internal consistency checks, and believe that this is the first direct measurement of a primordial abundance ratio. It provides the most accurate measurement of the baryon density: a high value of Ω b = 0.05, assuming a Hubble constant H 0 = 70 km s −1 Mpc −1 .Deuterium is rarely seen in QAS because the associated hydrogen is usually distributed over a wide range of velocities and its absorption covers deuterium. We selected QSO 1937-1009 because we found that the absorption system at z = 3.572 showed unusually weak metal lines in low resolution spectra, which we took to indicate that the gas was distributed in one or two narrow velocity components (11). We obtained optical spectra of QSO 1937-1009 (z em = 3.78, V ≃ 17.5) with the HIRES echelle spectrograph (12) on the W. M. Keck 10-m telescope. The high quality spectra make this amongst the best characterized QAS, and show strong absorption at the expected position of the D Lyα line and weak but highly significant absorption at D Lyβ .The weak metal lines in the system, C II, C IV, Si II, and Si IV, appear to have the same profiles, which are adequately described by two components separated by 15 km s −1 .

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supporting

confidence: 89%

mentioning

confidence: 93%

Cosmological baryon density derived from the deuterium abundance at redshift z = 3.57

Tytler

Fan

Burles

1996

Nature

305

281

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“…Can the claim that some of the nucleosynthetic baryons must be dark be circumvented by decreasing Ω B or increasing Ω V in some way? A few years ago the anomalously high deuterium abundance measured in some intergalactic Lyman-α clouds suggested that the nucleosynthesis value for Ω B could be lower than the standard one (Carswell et al 1994, Songaila et al 1994, Rugers & Hogan 1996, Webb at al. 1997).…”

Section: Evidence For Baryonic Dark Mattermentioning

confidence: 99%

Recent Developments in the Search for Baryonic Dark Matter

Carr

2001

Phase Transitions in the Early Universe: Theory and Observations

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Abstract. Cosmological nucleosynthesis calculations imply that many of the baryons in the Universe must be dark. We discuss the likelihood that some of these dark baryons may reside in galaxies as Massive Compact Halo Objects (MACHOs), the remnants of a first generation of pregalactic or protogalactic stars. Various candidates have been proposed for such remnants and we review the many types of observations which can be used to detect or exclude them. Claims to have found positive evidence for some of the candidates have generally turned out to be spurious or questionable, so the status of the MACHO scenario remains controversial. However, it would be premature to reject MACHOs altogether and further observations are likely to resolve the issue soon.

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“…However, it has been shown (Scully et al 1997) that by including the effects of outflow or galactic winds driven by supernovae heating in the early galaxy, the amount of deuterium destruction can be significantly larger when coupled to a steeply decreasing SFR. That such models exist is clearly of importance if the value of D/H in quasar absorption systems are as high as some observations indicate (Songaila et al 1994, Carswell et al 1994, Wampler 1996, Webb et al 1997.…”

Section: Introductionmentioning

confidence: 99%