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 $f_{\text{DM}}\simeq 0.01$ as the fraction of DM in PBHs with masses $10M_{\odot }-70M_{\odot }$. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around $M_{\text{halo}}\sim (50-55)M_{\text{PBH}}$. 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.

Comments: 9 pages, 3 figures. v2: New material added, especially in Secs. 2.2-2.3. References added. v3: Updated towards version accepted in Physics Letters B