  By coupling axions strongly to a hidden sector, the energy density in
coherent axions may be converted to radiative degrees of freedom, alleviating
the ``axion energy crisis''. The strong coupling is achieved by mixing the
axion and some other Goldstone boson through their kinetic energy terms, in a
manner reminiscent of paraphoton models. Even with the strong coupling it
proves difficult to relax the axion energy density through particle absorption,
due to the derivative nature of Goldstone boson couplings and the effect of
back reactions on the evolution of the axion number density. However, the
distribution of other particle species in the hidden sector will be driven from
equilibrium by the axion field oscillations. Restoration of thermal equilibrium
results in energy being transferred from the axions to massless particles,
where it can redshift harmlessly without causing any cosmological problems.
