The mysteries of the Universe continue to captivate scientists, among them dark matter—an enigmatic entity that, despite being dominant in space, remains largely unexplored. Recently, a groundbreaking theoretical study proposes a method that could be a turning point in the detection of this elusive matter using next-generation satellites.
This composite image shows the distribution of dark matter, galaxies, and hot gas in the core of the merging galaxy cluster Abell 520. Data from Chandra (in green) show the hot gas in the clusters and provide evidence that a collision occurred. Optical data from the Hubble Space Telescope and the Canada-France-Hawaii Telescope in Hawaii are presented in red, green, and blue. The light from stars within the cluster galaxies, which has been smoothed to show the location of most galaxies, is colored in orange. Confirming a previous observation, this result reveals that a cluster of dark matter is near most of the hot gas, where very few galaxies are visible.
Image Smithsonian Institution Dark matter, though undetectable directly, exerts an undeniable gravitational influence on visible matter. To unravel its secrets, Hyungjin Kim, a theoretical physicist at the DESY accelerator center in Germany, proposes the use of innovative gravitational wave detectors. These instruments, designed to measure subtle ripples in the fabric of space-time, could prove crucial in this quest.
Kim's research suggests that dark matter particles, present in large quantities in galactic halos, could be extremely light. These particles would behave more like classical electromagnetic waves, rather than material particles. This hypothesis opens new perspectives on the behavior of this elusive matter.
Kim likens these dark matter fluctuations to waves in the ocean, moving unpredictably and potentially spanning vast distances. If dark matter is indeed ultralight and wave-like, its movement could be detected by gravitational wave detectors.
According to Einstein's general theory of relativity, gravitational waves are disturbances in space-time. When such a wave passes through a gravitational wave detector, it temporarily alters the distance between two mirrors or similar objects within the detector. Kim hypothesizes that not only a gravitational wave but also a moving dark matter fluctuation could alter this distance.
The three spacecraft of the LISA mission will form a triangle in orbit, with sides of about 3.1 million miles (5 million kilometers) positioned behind the Earth. They will follow orbits similar to that of Earth, minimizing changes in the triangle side lengths.
Image NASA
However, current detectors like LIGO, which confirmed the existence of gravitational waves in 2015, lack the sensitivity to detect these dark matter fluctuations. That's why Kim is turning to future space-based gravitational wave detectors, where the distance between satellites would be significantly greater, potentially allowing the measurement of dark matter's influence.
Although implementing this theory could take more than a decade, with the planned launch of LISA (Laser Interferometer Space Antenna) by the European Space Agency in the 2030s, Kim is also exploring other methods to detect the influence of dark matter on space-time, notably through fast-spinning neutron stars.
This research opens new paths for understanding one of the Universe's greatest mysteries and could revolutionize our concept of dark matter.