No torque mechanism studied supplies enough angular momentum for the innermost light-PBH shells around a heavy seed, so the spike core is swallowed and far less dense than a WIMP spike.
Dark Matter Density Spikes around Primordial Black Holes
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abstract
We show that density spikes begin to form from dark matter particles around primordial black holes immediately after their formation at the radiation-dominated cosmological stage. This follows from the fact that in the thermal velocity distribution of particles there are particles with low velocities that remain in finite orbits around black holes and are not involved in the cosmological expansion. The accumulation of such particles near black holes gives rise to density spikes. These spikes are considerably denser than those that are formed later by the mechanism of secondary accretion. The density spikes must be bright gamma-ray sources. Comparison of the calculated signal from particle annihilation with the Fermi-LAT data constrains the present-day cosmological density parameter for primordial black holes with masses $M_{\rm BH}\geq10^{-8}M_\odot$ from above by values from $\Omega_{\rm BH}\leq1$ to $\Omega_{\rm BH}\leq10^{-8}$, depending on $M_{\rm BH}$. These constraints are several orders of magnitude more stringent than other known constraints.
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CMB data limits the s-wave annihilation cross section of thermal dark matter particles to ≲ 10^{-30} cm³/s scaled by PBH fraction and mass for PBHs heavier than ~10^{-10} solar masses.
citing papers explorer
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The swallowed spike: the formation of light primordial black hole structures around heavy seeds
No torque mechanism studied supplies enough angular momentum for the innermost light-PBH shells around a heavy seed, so the spike core is swallowed and far less dense than a WIMP spike.
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In-depth analysis of the clustering of dark matter particles around primordial black holes. Part III: CMB constraints
CMB data limits the s-wave annihilation cross section of thermal dark matter particles to ≲ 10^{-30} cm³/s scaled by PBH fraction and mass for PBHs heavier than ~10^{-10} solar masses.