First Results in the Search for Dark Matter from the GPS.DM Observatory

We present first results from the GPS.DM Observatory on our search for dark matter. Compelling cosmological evidence for dark matter includes its effect on galactic rotation, relativistic gravitational lensing, and its role in galactic formation and structure, including the galactic halo. Such evidence indicates that dark matter constitutes 25% of the total energy density of the Universe, as compared to only 5% for ordinary matter. Thus dark matter is about five times more prevalent than ordinary matter, yet conclusive evidence of dark matter interactions in terrestrial experiments remains elusive. It has been proposed [ref. 1] that dark matter may exist in the form of stable configurations of quantum fields that are ultralight, leading to the possible existence of dark matter objects such as topological defects that are spatially extended and large on the laboratory scale. If such dark matter objects interact with standard model particles, it is predicted that they could induce localized, temporary shifts in the apparent values of fundamental constants, such as the fine structure constant. In turn, this would lead to shifts in atomic transition frequencies, which would cause pairs of initially synchronized clocks to become desynchronized. Here we use the GPS satellite constellation and network of Earth-based receiver stations as a 50,000 km aperture sensor array to search for signals of exotic physics, such as spatially extended dark matter objects. Statistical mechanics predicts that dark matter's velocity relative to the Earth is at galactic rotation speeds of 300 km/s, transiting across the aperture of the GPS constellation on the timescale of 200 s. On this timescale, we seek coordinated patterns of atomic clock transients from multiple GPS satellites, by analyzing over a decade of satellite Rb clock data at 30-s intervals. We find no coordinated patterns that exceed a signal level of 0.43 ns, which enables us to improve limits on the energy scale for certain models of dark matter and dark energy by up to six orders of magnitude. [1] Derevianko, A. and M. Pospelov (2014). Nature Physics 10, 933.