  Sun-like stars can transmute into comparable mass black holes by steadily
accumulating heavy non-annihilating dark matter particles over the course of
their lives. If such stars form in binary systems, they could give rise to
quasi-monochromatic, persistent gravitational waves, commonly known as
continuous gravitational waves, as they inspiral toward one another. We
demonstrate that next-generation space-based detectors, e.g., Laser
Interferometer Space Antenna (LISA) and Big Bang Observer (BBO), can provide
novel constraints on dark matter parameters (dark matter mass and its
interaction cross-section with the nucleons) by probing gravitational waves
from transmuted Sun-like stars that are in close binaries. Our projected
constraints depend on several astrophysical uncertainties, nevertheless, are
competitive with the existing constraints obtained from cosmological
measurements as well as terrestrial direct searches, demonstrating a notable
science-case for these space-based gravitational wave detectors as probes of
particle dark matter.
