Probing Dark Matter Clumps, Strings and Domain Walls with Gravitational
  Wave Detectors
  Gravitational wave astronomy has recently emerged as a new way to study our
Universe. In this work, we survey the potential of gravitational wave
interferometers to detect macroscopic astrophysical objects comprising the dark
matter. Starting from the well-known case of clumps we expand to cosmic strings
and domain walls. We also consider the sensitivity to measure the dark matter
power spectrum on small scales. Our analysis is based on the fact that these
objects, when traversing the vicinity of the detector, will exert a
gravitational pull on each node of the interferometer, in turn leading to a
differential acceleration and corresponding Doppler signal, that can be
measured. As a prototypical example of a gravitational wave interferometer, we
consider signals induced at LISA. We further extrapolate our results to
gravitational wave experiments sensitive in other frequency bands, including
ground-based interferometers, such as LIGO, and pulsar timing arrays, e.g. ones
based on the Square Kilometer Array. Assuming moderate sensitivity improvements
beyond the current designs, clumps, strings and domain walls may be within
reach of these experiments.
