  We discuss the sensitivity of the present and near-future axion dark matter
experiments to a halo of axions or axion-like particles gravitationally bound
to the Earth or the Sun. The existence of such halos, assuming they are formed,
renders a significant gain in the sensitivity of axion searches while
satisfying all the present experimental bounds. The structure and coherence
properties of these halos also imply novel signals, which can depend on the
latitude or orientation of the detector. We demonstrate this by analysing the
sensitivity of several distinct types of axion dark matter experiments.

High Energy Physics - Phenomenology;Cosmology and Nongalactic Astrophysics;Atomic Physics