Astronomers create a new technique to aid the search for dark matter

Meteorites may help astronomers devise a new way to track down dark matter — mysterious, invisible particles that until now have only been detected because of their effect on the natural world.

Five times more abundant than ordinary matter, dark matter makes up about 85% of the total mass of the universe and about a quarter (26.8%) of the total mass and energy of the universe. Humans are unable to detect these elusive particles directly, since dark matter does not emit light, so scientists use powerful instruments like the Hubble Space Telescope or the next one from NASA Nancy Grace Roman Space Telescope to witness its influence on galaxies and other distant star clusters.

Now, according to a study led by Ohio State University researchers, ground-based radar systems could be used to aid in the search.

John Beacom, co-author of the study and professor of physics and astronomy at Ohio Statesaid that while scientists usually look for only tiny dark matter particles with small masses, the goal of this new research is to improve the search by helping to characterize macroscopic dark matter — particles with large masses that may not reach the traditional terrestrial detectors.

“One of the reasons dark matter is so hard to detect could be because the particles are so massive.” Beacom said “If the mass of dark matter is small, then the particles are common, but if the mass is large, the particles are rare.”

Although these particles cannot be touched or seen, dark matter can be perceived by its gravitational effects on other celestial phenomena, such as stars or black holes.

While its effects on other natural systems aren’t easy to categorize, taking the time to learn more about dark matter opens new avenues for scientists to understand the size, shape and future of the cosmos, Beacom said. These detections can also reveal the mass of these particles, which, depending on their size, can have enormous effects on the formation and structure of galaxies.

The research is currently published on the open access preprint server, archiv.

What makes the research so novel is that the scientists applied the same technology used to track meteors as they streak across the sky. As they pass through Earth’s atmosphere, both meteors and dark matter particles produce deposits of ionization, a form of radiation that leaves behind free electrons, atoms capable of conducting electricity. The electromagnetic waves released by the radar bounce off the free electrons, indicating the presence of otherworldly matter, which can then be used to distinguish dark matter from meteors. In this way, the atmosphere of the entire planet can be transformed into an efficient and large-scale particle detector.

Although scientists have used this meteor-hunting method for decades, Beacom said he was surprised that no one had ever applied these systems, or their previously collected data, to the search for dark matter.

One of the study’s most significant findings is how the team’s new method could complement other cosmological searches for dark matter, as their system offers a level of precision and sensitivity that many other techniques lack.

“Current cosmology techniques are quite sensitive, but they have no way to check their own work,” Beacom said. “This is a brand new technique, so if scientists aren’t sure what they’ve detected, a signal from cosmology could be checked in detail with the radar technique.”

Co-authors Pawan Dhakal, Steven Prohira and Christopher Cappiello of Ohio State;

This work was supported by the National Science Foundation.

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