Implications for dark matter direct detection in the presence of LIGO-motivated primordial black holes

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 fDM≃0.01 as the fraction of DM in PBHs with masses 10M⊙−70M⊙. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around Mhalo∼(50−55)MPBH. 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.