Gamma-rays from ultracompact minihalos: potential constraints on the primordial curvature perturbation

Understand

Ultracompact minihalos (UCMHs) are dense dark matter structures which can form from large density perturbations shortly after matter-radiation equality.

• If dark matter is in the form of Weakly Interacting Massive Particles (WIMPs), then UCMHs may be detected via their gamma-ray emission.
• We investigate how the {\em{Fermi}} satellite could constrain the abundance of UCMHs and place limits on the power spectrum of the primordial curvature perturbation.
• Detection by {\em Fermi} would put a lower limit on the UCMH halo fraction.