Researchers at the ARC Centre of Excellence for Dark Matter Particle Physics (CDM) and the University of Western Australia have built a two-centimeter detector that in its first 153 days of operation has detected a couple of events that researchers believe could be high-frequency gravitational waves, which have never been witnessed before. These types of waves would have been created by a primordial black hole or a cloud of dark matter particles.
Low-frequency gravitational waves are caused by two black holes spinning and merging into each other or a star disappearing into a black hole. Most research has focused on these low-frequency waves but there is also a significant amount of theoretical proposals for high-frequency gravitational wave sources as well.
The new detector may be able to pick up high-frequency gravitational waves because it is built around a quartz crystal bulk acoustic wave resonator that can vibrate at high frequencies due to acoustic waves traveling through its thickness. Those waves induce an electric charge that’s picked up by conducting plates and amplified into a signal that's easier for researchers to spot.
So far, the resonator detected some activity on May 12, 2019, and on November 27, 2019. The potential explanations for this activity were published this month in the journal Physical Review Letters.
"It's exciting that this event has shown that the new detector is sensitive and giving us results, but now we have to determine exactly what those results mean," University of Western Australia researcher and co-author of the paper William Campbell said in a press release.
Campbell added that he and his team have demonstrated for the first time ever that these devices can be used as highly sensitive gravitational wave detectors and that this experiment is one of only two currently active in the world searching for high-frequency gravitational waves at these frequencies. The development of this technology could potentially provide new insight into this area of gravitational wave astronomy.
However, until the researchers manage to prove the activity detected was indeed high-frequency gravitational waves, there remains the possibility that the events were something else such as a meteor event or an internal atomic process. To this end, the physicists are working on new detectors.
"The next generation of the experiment will involve building a clone of the detector and a muon detector sensitive to cosmic particles. If two detectors find the presence of gravitational waves, that will be really exciting," Campbell concluded.