Primordial lithium problem
The primordial lithium problem (also cosmological lithium problem ) describes the low frequency of 7 Li in ancient stars by a factor of 2–3 compared to the expected results of primordial nucleosynthesis , a theory about the formation of the first atomic nuclei shortly after the Big Bang .
According to the standard cosmological model , all baryonic matter in the universe was created within the first three minutes from the expansion of a singularity through primordial nucleosynthesis. The theory describes the frequency of the resulting elements hydrogen , deuterium and helium with high accuracy. These predictions have been confirmed for helium and deuterium within the scope of the measurement accuracy through observations of galaxies with high redshifts . In contrast, the observed incidence of lithium-7 is a factor of 2–3 with a significance of 4–5 standard deviations below the expected value .
The cosmological lithium problem was first detected in white dwarfs in the halo of the Milky Way and can now also be observed in a number of Population II stars with low metallicity .
Three basic solutions have been proposed to solve the problem:
- Astrophysical solutions try to explain the lower abundance of 7 Li as a consequence of its unexpectedly effective destruction by thermonuclear reactions inside the first generation of stars.
- Solutions in the field of nuclear physics explain the deviations through changes in the rates of nuclear reaction in the formation or destruction of lithium.
- Solutions beyond the standard model of cosmology take into account the decay of dark matter , supersymmetry or alternative cosmological models.
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- Brian D. Fields: The Primordial Lithium Problem . In: Astrophysics. Solar and Stellar Astrophysics . 2012, doi : 10.1146 / annurev-nucl-102010-130445 , arxiv : 1203.3551v1 .
- M. Spite, F. Spite, P. Bonifacio: The cosmic lithium problem: an observer's perspective . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1208.1190v2 .
- Alain Coc, Jean-Philippe Uzan, Elisabeth Vangioni: Mirror matter can alleviate the cosmological lithium problem . In: Astrophysics. Solar and Stellar Astrophysics . 2012, arxiv : 1303.1935v1 .