The finding, published in the journal Physical Review Letters, could have major implications for our understanding of the universe. Dark matter is thought to be the scaffolding on which galaxies are built, and it is responsible for the observed gravitational effects that we see on the largest scales. However, we don't know what dark matter is made of, and it has never been directly detected.
The new research used data from the Dark Energy Survey, a massive international project that is surveying the universe in visible and near-infrared light. The team of scientists looked for gravitational lensing, the bending of light by massive objects, caused by dark matter. They found less lensing than expected, suggesting that dark matter may be less dense than previously thought.
"Our results suggest that the density of dark matter in the universe is about half of what has been traditionally assumed," said lead author Chihway Chang, a postdoctoral researcher at the University of Chicago. "This is a significant finding that could change our understanding of how the universe works."
The researchers say that their findings could be explained by a number of different scenarios. One possibility is that dark matter is made up of particles that are lighter than previously thought. Another possibility is that dark matter is not evenly distributed throughout the universe, but is instead clumped together in certain areas.
The team plans to continue their research to try to determine what is causing the discrepancy between their observations and the traditional assumptions about dark matter.
"This is a very exciting time in cosmology," said co-author Joshua Frieman, the director of the Dark Energy Survey. "We're learning more about dark matter and the universe all the time, and we're making progress toward one day understanding what makes up the majority of the universe."
