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Cosmological implications of light element abundances: theory
1Astronomy and Astrophysics Centers 140, University of Chicago, Chicago, IL 60637, USA.
Summary
Primordial nucleosynthesis and cosmic microwave background radiation are key tests for the Big Bang model. Light element abundances and neutrino counts support the standard model, indicating a need for dark matter.
Area of Science:
- Cosmology
- Nuclear Physics
- Particle Physics
Background:
- The hot Big Bang model is supported by cosmic microwave background radiation and primordial nucleosynthesis.
- Light element abundances provide quantitative tests for cosmological models.
Purpose of the Study:
- To test the standard Big Bang cosmological model against alternative scenarios.
- To analyze the implications of light element abundances and neutrino counts for cosmology.
Main Methods:
- Comparing standard homogeneous-isotropic Big Bang calculations with observed light element abundances (1H, 4He, 2H, 3He, 7Li).
- Evaluating the impact of quark-hadron-induced inhomogeneities on nucleosynthesis predictions.
- Incorporating recent experimental results on the number of neutrinos (Nnu) from colliders.
Main Results:
- Standard model accurately predicts observed light element abundances.
- Alternative scenarios with inhomogeneities, when fitted to abundances, yield similar baryonic density (Omegab ≈ 0.06).
- Nnu results from colliders support the standard Big Bang scenario.
Conclusions:
- The Big Bang model is robust, supported by light element abundances and Nnu.
- The low baryonic density (Omegab ≈ 0.06) necessitates nonbaryonic dark matter and potentially dark baryonic matter.
- Population II B and Be observations are attributed to cosmic ray spallation, not primordial nucleosynthesis.
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