New Study Reveals Dark Matter Acts Like Ordinary Matter

A recent study from the University of Geneva suggests that dark matter may behave similarly to ordinary matter, adhering to established physical laws despite its elusive nature. The research, published in Nature Communications, analyzes the movement of galaxies through cosmic gravitational wells, revealing that dark matter appears to follow predictable patterns akin to those of visible matter.

The challenge of understanding dark matter stems from its invisibility; it neither emits nor reflects light, making it difficult to study directly. Researchers sought to determine if dark matter interacts with the same fundamental forces as ordinary matter or if it is influenced by a potential fifth force yet to be identified.

Investigating Dark Matter’s Behavior

The research team examined how dark matter interacts with gravitational wells, which are formed by massive objects that distort space. These wells pull in ordinary matter—like planets and stars—according to well-established principles rooted in Einstein’s general relativity and Euler’s equations.

Camille Bonvin, an associate professor in the Department of Theoretical Physics at UNIGE and co-author of the study, explained, “We compared the velocities of galaxies across the Universe with the depth of gravitational wells. If dark matter is not subject to a fifth force, then galaxies—largely composed of dark matter—will fall into these wells like ordinary matter, governed solely by gravity.”

The study’s findings indicate that dark matter indeed sinks into gravitational wells in a manner consistent with ordinary matter. However, the research does not completely rule out the presence of an unknown force influencing this behavior.

Potential for New Discoveries

Nastassia Grimm, the first author of the study and former postdoctoral researcher at UNIGE, noted, “If such a fifth force exists, it cannot exceed 7% of the strength of gravity; otherwise, it would have been detected in our analyses.” This insight is significant given that dark matter is believed to be approximately five times more abundant than ordinary matter, making any new findings crucial for understanding its role in the cosmos.

The researchers emphasize that the next step is to further investigate whether a subtle fifth force influences dark matter. Isaac Tutusaus, a researcher at ICE-CSIC and IEEC and an associate professor at the Midi-Pyrénées observatory at the University of Toulouse, highlighted the importance of forthcoming experiments. “Upcoming data from the newest experiments, such as LSST and DESI, will be sensitive to forces as weak as 2% of gravity. They should therefore allow us to learn even more about the behavior of dark matter,” he concluded.

This study represents a significant advancement in the quest to unravel the mysteries of dark matter, paving the way for future research that could reshape our understanding of the Universe.