Is deuterium in high-redshift Lyman limit systems primordial?

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Astrophysical Journal

DOI:https://doi.org/10.1086/304288· OSTI ID:542143

Jedamzik, K ^[1]; Fuller, G M ^[2]

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1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)
2. Department of Physics, University of California, 9500 Gilman Drive, San Diego, La Jolla, California 92093-0319 (United States)

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 observed are significantly discordant. Assuming the validity of all the data, if this discordance does not reflect intrinsic primordial inhomogeneity, then it must arise from processes operating after the primordial nucleosynthesis epoch. We consider processes that might lead to significant deuterium production or destruction and yet allow the cloud to mimic a chemically unevolved system. These processes include, for example, anomalous/stochastic chemical evolution and D/{sup 4}He photodestruction. In general, we find it unlikely that these processes could have significantly altered D/H in Lyman limit clouds. We argue that chemical evolution scenarios, unless very finely tuned, cannot account for significant local deuterium depletion since they tend to overproduce {sup 12}C, even when allowance is made for possible outflow. Similarly, D/{sup 4}He photodestruction schemes engineered to locally produce or destroy deuterium founder on the necessity of requiring an improbably large {gamma}-ray source density. Future observations of D/H in Lyman limit systems may provide important insight into the initial conditions for the primordial nucleosynthesis process, early chemical evolution, and the galaxy formation process. {copyright} {ital 1997} {ital The American Astronomical Society}

• Research Organization: Lawrence Livermore National Laboratory
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 542143
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 483; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
COSMOLOGY
DEUTERIUM
ELEMENT ABUNDANCE
ISOTOPE RATIO
LYMAN LINES
NUCLEOSYNTHESIS
PHOTONUCLEAR REACTIONS
QUASARS
RED SHIFT