Gravitational wave microlensing by dressed primordial black holes

Abstract

We study gravitational wave microlensing by primordial black holes (PBHs), accounting for the effect of a particle dark matter minihalo surrounding them. Such minihaloes are expected when PBHs make up only a fraction of all dark matter. We find that the LIGO-Virgo detections imply a $1\sigma$ bound on the abundance of PBHs heavier than $50 M_{\odot}$. The next generation observatories can potentially probe PBHs as light as $0.01 M_\odot$ and down to $2\times10^{-4}$ fraction of all dark matter. We also show that these detectors can distinguish between dressed and naked PBHs, providing a novel way to study the distribution of particle dark matter around black holes and potentially shed light on the origins of black holes.