Dark matter from the depths of the universe

From multi-messenger astronomy to the search for dark matter

Multi-messenger astronomy involves the coordinated observation of disparate signals that stem from the same astrophysical event. Since the first detection of gravitational waves with the LIGO interferometer several years ago, the interest in this field has expanded enormously and it has yielded a tremendous amount of new information originating from the depths of the universe. "When gravitational waves are generated somewhere in space and detected on Earth, numerous telescopes now focus on the event to record various signals, such as those in the form of electromagnetic radiation, for instance," explains Arne Wickenbrock. "We asked ourselves what would happen if part of the observed energy released by such events was also radiated in the form of exotic low-mass fields or ELFs. Would we be able to detect them with our existing networks of quantum sensors?"

The scientists' calculations have confirmed that this could be the case for certain parameters. "We also reasoned that such fields, when radiated, would cause a characteristic frequency signature in the networks," adds Arne Wickenbrock. "The signal would be similar to the sound of a passing siren, sweeping from high to low frequencies." The researchers have two particular networks in mind: the worldwide GPS network of atomic clocks and the GNOME network, which is comprised of a multitude of magnetometers distributed around the globe. On the basis of the expected strength of the signal, the GPS system should currently be sensitive enough to detect ELFs. The work group of JGU Professor Dmitry Budker at HIM, together with other teams, is currently upgrading the GNOME network, and on completion this should also be sensitive enough to observe such events.

Potential ELFs are of particular significance in the search for dark matter. Although we know this strange form of matter must exist, nobody yet knows what it is made of. Specialists are considering and researching a whole range of possible particles that might theoretically qualify as candidates. Among the most promising current candidates are extremely light bosonic particles, which can also be seen in terms of a classic field oscillating at a particular frequency. "Thus, in the depths of the universe, dark matter in the form of ELFs may be created during the merger of two black holes," concludes Arne Wickenbrock. "Precision quantum sensor networks, in turn, could function as ELF telescopes, adding another important element to the toolbox of multi-messenger astronomy."