  If the symmetry breaking leading to the origin of the axion dark matter field
occurs after the end of inflation and is never restored, then overdensities in
the axion field collapse to form dense objects known in the literature as axion
miniclusters. The estimates of the typical minicluster mass and radius strongly
depend on the details of the cosmology at which the onset of axion oscillations
begin. In this work we study the properties and phenomenology of miniclusters
in alternative cosmological histories and find that they can change by many
orders of magnitude. Our findings have direct implications on current and
future experimental searches and, in the case of discovery, could be used to
learn something about the universe expansion prior to Big-Bang-Nucleosynthesis.
