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arXiv · 1104.4507

Axion Dark Matter and Cosmological Parameters

O. Erken·P. Sikivie·H. Tam·Q. Yang
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Abstract

We observe that photon cooling after big bang nucleosynthesis (BBN) but before recombination can remove the conflict between the observed and theoretically predicted value of the primordial abundance of $^7$Li. Such cooling is ordinarily difficult to achieve. However, the recent realization that dark matter axions form a Bose-Einstein condensate (BEC) provides a possible mechanism, because the much colder axions may reach thermal contact with the photons. This proposal predicts a high effective number of neutrinos as measured by the cosmic microwave anisotropy spectrum.

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O. Erken, P. Sikivie, H. Tam, Q. Yang. 2012-01-23. Axion Dark Matter and Cosmological Parameters. https://doi.org/10.1103/physrevlett.108.061304

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