Simulations of Axion Minihalos

Understand

The axion, motivated as a solution to the strong CP problem, is also a viable dark matter candidate.

• We use N-body simulations to study the formation of substructures from white-noise density fluctuations.
• The density profiles of our relaxed axion minihalos can be described by the Navarro-Frenk-White profile, and the minihalos' concentration number agrees well with a simple, physically-motivated model.
• We develop a semi-analytic formula to fit the mass function from our simulation, which agrees broadly at different redshifts and only differs at factor of two level from classic halo mass functions.