The abundance of primordial black holes from the global 21cm signal and extragalactic gamma-ray background

Understand

Primordial black holes (PBHs) formed in the early Universe can accret dark matter particles due to gravity and form ultracompact minihalos (UCMHs).

• The theoretical researches and simulations have shown that the density profile of dark matter in UCMHs is in the form of $\rho (r) \sim r^{-2.25}$.
• Compared with the popular dark matter halo model, e.g.
• NFW model, dark matter annihilation rate is larger in UCMHs.