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 ${10}^{16}$ and ${10}^{20}\mathrm{g}$, 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 $3\times {10}^{-15}\mathrm{m}/{\mathrm{s}}^{\mathrm{2}}/{\mathrm{H}\mathrm{z}}^{1/2}$ down to $\sim {10}^{-5}\mathrm{H}\mathrm{z}$ is achieved by the Laser Interferometer Space Antenna, the event rate, with signal-to-noise ratios greater than 5, could become $\sim 0.1$ per decade, involving black holes of mass $\sim {10}^{17}\mathrm{g}$. 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 $\sim {10}^{16}\mathrm{g}$ 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.