Radio bounds on the mixed dark matter scenarios of primordial black holes and WIMPs

Abstract

We study the synchrotron radio emission in the mixed dark matter scenarios consisting of the primordial black holes (PBHs) and the self-annihilating WIMPs (weakly interacting massive particles). The WIMPs can form the ultracompact minihalos around PBHs and the annihilation enhancement from these dense halos can lead to the efficient synchrotron radiation at the radio frequency in the presence of galactic magnetic fields. The upper bound of PBH fraction with respect to the total dark matter abundance is of order 10 −8 ∼ 10 −5 depending on the electroweak scale WIMP mass (mχ = 10 ∼ 1000 GeV) and the WIMP annihilation channel (e.g. a hadronic χχ → b b or a leptonic χχ → e + e − channel). The PBH contribution to the total dark matter abundance is hence negligible when the other component of dark matter is composed of the conventional electroweak scale WIMPs.

Constraints on primordial black holes with CMB spectral distortions

“…Note that the limits are independent on the PBH mass, and similar features can be also found in previous works [26,30,35,61,62]. In fact, since the annihilation rate of the DM particle within UCMH is proportional to the PBH mass Γ anni ∝ M PBH , the energy injection rate per unit volume is…”