Primordial Black Holes Proposed as Explanation for Lithium-7 Abundance Discrepancy
A new theoretical model suggests primordial black holes could explain why observed lithium-7 abundance in the early universe is lower than predictions from Big Bang nucleosynthesis. The mechanism involves neutron capture transforming lithium-7 into heavier isotopes that decay into helium-4. This addresses a long-standing puzzle in cosmology where theory and observations have disagreed on primordial element abundances.
Researchers propose that primordial black holes—hypothetical black holes formed in the early universe—could resolve the lithium-7 problem, a discrepancy between theoretical predictions and observed abundances of this element from the Big Bang. The model works through baryons evaporated by primordial black holes, which enable neutron capture processes that convert excess lithium-7 into lithium-8 or beryllium-8. These heavier isotopes rapidly decay into pairs of helium-4 nuclei, effectively reducing the lithium-7 abundance to match observations. The proposed mechanism offers a potential solution to a problem that has challenged cosmologists for decades, as standard Big Bang nucleosynthesis predicts roughly three times more lithium-7 than is observed in old stars and the intergalactic medium.
What's missing
The study does not discuss observational constraints on the abundance or properties of primordial black holes required for this mechanism to work, nor does it address how this scenario compares quantitatively to other proposed solutions to the lithium problem (such as nuclear physics uncertainties or non-standard Big Bang scenarios).
What different sources said
- arXiv astro-phCenter
Possible explanation of primordial $^7$Li deficit
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