Search for small-mass black-hole dark matter with space-based gravitational wave detectors

If the halo dark matter were composed of primordial black holes (PBHs) with mass between 10¹⁶ and 10²⁰   g, their gravitational interaction with test masses of laser interferometer may lead to a detectable pulselike signal during the fly-by. If a proof-mass noise of 3×10^-15   m/s²/Hz^1/2 down to ∼10^-5  Hz is achieved by the Laser Interferometer Space Antenna, the event rate, with signal-to-noise ratios greater than 5, could become ∼0.1 per decade, involving black holes of mass ∼10¹⁷   g. The detection rate could improve significantly for future space-based interferometers, though these events must be distinguished from those involving perturbations due to near-Earth asteroids. While the presence of primordial black holes below a mass of ∼10¹⁶   g is now constrained based on the radiation released during their evaporation, the gravitational-wave detectors could potentially extend the search for PBHs to several orders of magnitude higher masses.