Constraints on primordial black holes with CMB spectral distortions

In the mixed dark matter scenarios consisting of primordial black holes (PBHs) and weakly interacting massive particles (WIMPs), WIMPs can be accreted onto PBHs to form ultracompact minihalos (UCMHs) with a density spike in early universe. Compared classical halo, UCMHs are formed earlier have higher center. Since annihilation rate is proportional squared number WIMPs, it expected that within enhanced has influences on Between time recombination matter-radiation equality, energy released from injected into Universe resulting cosmic microwave background $y$-type distortion. We investigate these effects derive upper limits abundance taking advantage observational results far infrared absolute spectrophotometer (FIRAS). find for mass range $1\ensuremath{\le}{m}_{\ensuremath{\chi}}\ensuremath{\le}1000\text{ }\text{ }\mathrm{GeV}$, $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\ensuremath{\le}{\mathrm{\ensuremath{\Omega}}}_{\mathrm{PBH}}\ensuremath{\le}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$.