A Robust Test of the Existence of Primordial Black Holes in Galactic Dark Matter Halos

Understand

If very low mass primordial black holes (PBH) within the asteroid/moon-mass range indeed reside in galactic dark matter halos, they must necessarily collide with galactic neutron stars (NSs).

• These collisions must, again necessarily, form light black holes (LBHs) with masses of typical NSs, $M_{\rm LBH} \approx \,1-2\,M_{\odot}$.
• LBHs may be behind events already detected by ground-based gravitational-wave detectors (GW170817, GW190425, and others such as a mixed stellar black hole-neutron star mass event GW191219_163120), and most recently by microlensing (OGLE-BLG-2011-0462).
• Although the status of these observations as containing LBHs is not confirmed, there is no question that gravitational-wave detectors and microlensing are in principle and in practice capable of detecting LBHs.