Dark Matter Decay and the Abundance of Ultracompact Minihalos

Understand

Ultracompact minihalos would be formed if there are larger density perturbations ($0.0003 < \delta\rho/\rho < 0.3$) in the earlier epoch.

• The density profile of them is steeper than the standard dark matter halos.
• If the dark matter can annihilate or decay into the standard particles, e.g., photons, these objects would be the potential astrophysical sources.
• In order to be consistent with the observations, such as $Fermi$, the abundance of ultracompact minihalos must be constrained.