Search for domain wall dark matter with atomic clocks on board global
  positioning system satellites
  Cosmological observations indicate that 85% of all matter in the Universe is
dark matter (DM), yet its microscopic composition remains a mystery. One
hypothesis is that DM arises from ultralight quantum fields that form
macroscopic objects such as topological defects. Here we use GPS as a ~ 50,000
km aperture DM detector to search for such defects in the form of domain walls.
GPS navigation relies on precision timing signals furnished by atomic clocks
hosted on board GPS satellites. As the Earth moves through the galactic DM
halo, interactions with topological defects could cause atomic clock glitches
that propagate through the GPS satellite constellation at galactic velocities ~
300 km/s. Mining 16 years of archival GPS data, we find no evidence for DM in
the form of domain walls at our current sensitivity level. This allows us to
improve the limits on certain quadratic scalar couplings of domain wall DM to
standard model particles by several orders of magnitude.
