  Signal estimates for direct axion dark matter searches have used the
isothermal sphere halo model for the last several decades. While insightful,
the isothermal model does not capture effects from a halo's infall history nor
the influence of baryonic matter, which has been shown to significantly
influence a halo's inner structure. The high resolution of cavity axion
detectors can make use of modern cosmological structure-formation simulations,
which begin from realistic initial conditions, incorporate a wide range of
baryonic physics, and are capable of resolving detailed structure. This letter
uses a state-of-the-art cosmological N-body+Smoothed-Particle Hydrodynamics
simulation to develop an improved signal model for axion cavity searches.
Signal shapes from a class of galaxies encompassing the Milky Way are found to
depart significantly from the isothermal sphere. A new signal model for axion
detectors is proposed and projected sensitivity bounds on the Axion Dark Matter
eXperiment data are presented.
