Implications for Dark Matter Direct Detection in the Presence of LIGO-Motivated Primordial Black Holes

TL;DR

This paper explores how dark matter mini-halos around primordial black holes, motivated by LIGO observations, could impact direct detection experiments by reducing local dark matter density and altering detection prospects.

Contribution

It introduces a model of dark matter mini-halos around primordial black holes and analyzes their survival and effect on direct detection experiments.

Findings

Mini-halos are resistant to tidal disruption in the Milky Way.

Presence of mini-halos could halve the local dark matter density.

Detection chances of dark matter are potentially reduced by mini-halos.

Abstract

We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider $f_{\textrm{DM}} \simeq 0.01$ as the fraction of DM in PBHs with masses $10 M_{\odot} - 70 M_{\odot}$. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around $M_{\textrm{halo}} \sim (50-55) M_{\textrm{PBH}}$. We analyze the effect of tidal forces acting on dressed PBHs within the Milky Way galaxy. In the solar neighborhood, the mini-halos are resistant against tidal disruption from the mean-field potential of the galaxy and encounters with stars, but they undergo a small level of disruption caused by disk shocking. The presence of mini-halos around LIGO-motivated PBHs today could reduce by half the local dark matter background. High-resolution simulations are encouraged. If the proposed scenario is realized, chances of direct detection of DM would decrease.