Progress in dark matter search with the global positioning system*

The microscopic composition of dark matter remains a mystery, but it could arise from ultralight quantum fields that form macroscopic objects. By analyzing the global positioning system (GPS) satellite atomic clock data, it is possible to search for transient signatures of exotic physics, such as “clumpy” dark matter, by using the GPS constellation as a 50,000 km aperture sensor array. Interactions with domain walls could cause a sequence of atomic clock perturbations that propagate through the satellite constellation at galactic velocities ~ 300 km/s. In initial searches in 16 years of archival data, we found no evidence for domain walls, which improved the limits on certain quadratic scalar couplings of domain wall dark matter to standard model particles by several orders of magnitude [1]. We now characterize two data analysis methods for improving these limits:  (i) a matched filter technique and (ii) a Bayesian statistics method [2]. We show that these techniques can improve upon our previously established constraints on dark matter couplings by two orders of magnitude. Details in: Roberts et al., Nat. Commun., 97, 083009 (2017);  Roberts et al., Phys. Rev. D, 118, 221102 (2018).