Probing exotic fields with networks of atomic clocks11 Sep 2019
An exotic light field (ELF) is a class of field beyond the standard model that could be produced in high-energy astrophysical events with enough amplitude to be detected with precision measurement sensors. A model that describes an ELF as a pulse of ultra-relativistic matter waves and an estimate of the sensitivity for current and future networks of atomic clocks to detect ELFs is developed here. The global positioning system (GPS) is presented as an existing network of atomic clocks that has the potential to probe ELFs. A first proof-of-principle search for ELFs emitted as bursts from the GW170817 neutron star merger was performed with data from GPS. Although no concrete evidence was found for ELFs, a foundation has been produced for future searches for ELFs originating from many other astrophysical events, such as gamma ray bursts, black hole mergers, and solar flares for the last 20 years of GPS operation.
In this work we have demonstrated the ability of global networks of precision measurement devices to detect ELFs that may be emitted from high energy astrophysical events, potentially making them a new messenger in the growing field of multimessenger astronomy. We discussed using the atomic clocks that make up GPS as such a network, along with future networks of atomic clocks, and we characterized how ELFs may interact with them. We have developed a model for the time evolution of pulses of ultrarelativistic matter waves, and estimated the sensitivity of GPS and future networks of atomic clocks to detect ELFs. We have shown that quadratic couplings to ELFs have great potential for detection with GPS and that future networks of atomic clocks have even greater sensitivity. This work has also uncovered previously unknown time-frequency behavior of the GPS satellite clocks, as our analysis is the first to be preformed on high-rate GPS clock data. While we have shown that these time-frequency signals are not likely caused by ELFs, their origin still remains a mystery and certainly invokes questions about the behavior of the GPS network. A complete characterization of the clock behavior we have discovered could be used to improve the modeling and quality of GPS. The search for ELFs based on this event was limited in this case due to the limited data available, but this search can be extended to times much longer after the GW170817 event itself to consider ELFs of slower (though still ultra-relativistic) velocities. Future work in the search for ELFs can include analysis at known times of past astrophysical events, such as gamma ray bursts, black hole mergers, and solar flares.