# WIMPs and stellar-mass primordial black holes are incompatible

## TL;DR

This paper investigates the coexistence of primordial black holes and WIMPs as dark matter, showing that their simultaneous presence leads to incompatible observational constraints due to gamma-ray signals.

## Contribution

It demonstrates that the formation of steep density profile halos around PBHs is consistent with theory, but their coexistence with WIMPs is constrained by gamma-ray observations.

## Key findings

- PBHs constitute at most one billionth of dark matter for certain masses.
- Detection of PBHs would exclude WIMPs as dominant dark matter.
- Steep density halos form around PBHs in simulations.

## Abstract

We recently showed that postulated ultracompact minihalos with a steep density profile do not form in realistic simulations with enhanced initial perturbations. In this paper we assume that a small fraction of the dark matter consists of primordial black holes (PBHs) and simulate the formation of structures around them. We find that in this scenario halos with steep density profiles do form, consistent with theoretical predictions. If the rest of the dark matter consists of weakly interacting massive particles (WIMPs), we also show that WIMPs in the dense innermost part of these halos would annihilate and produce a detectable gamma-ray signal. The non-detection of this signal implies that PBHs make up at most one billionth of the dark matter, provided that their mass is greater than one millionth of the mass of the Sun. Similarly, a detection of PBHs would imply that the remaining dark matter could not be WIMPs.