Thermal axion constraints in non-standard thermal histories

Daniel Grin, Tristan Smith, Marc Kamionkowski, David B. Tanner, Karl A. van Bibber
There is no direct evidence for radiation domination prior to big-bang nucleosynthesis, and so it is useful to consider how constraints to thermally-produced axions change in non-standard thermal histories. In the low-temperature-reheating scenario, radiation domination begins as late as ∼ 1 MeV, and is preceded by significant entropy generation. Axion abundances are then suppressed, and cosmological limits to axions are significantly loosened. In a kination scenario, a more modest change to
more » ... modest change to axion constraints occurs. Future possible constraints to axions and low-temperature reheating are discussed.
doi:10.1063/1.3489561 fatcat:yibfydjbbffpjn5ll2giyuppdu