Researchers at the University of Waterloo have developed the first-ever composite image of dark matter, new research published in the Monthly Notices of the Royal Astronomical Society reports.
Dark matter is a mysterious substance that is thought to make up about 25 percent of the universe. However, as it does not shine, absorb, or reflect light, it is nearly impossible to detect. This makes the new picture the first physical proof that galaxies are connected by webs of dark matter.
Scientists have suspected dark matter’s role in the universe for some time, but they have never been able to look at or study the webs. The new research overcomes this obstacle through gravitational lensing — the process astronomers use to study the light in distant galaxies.
Lensing works by allowing the images of distant galaxies to warp slightly under the influence of an unseen mass such as a planet, black hole, or dark matter, UPI reports.
Typically, this process is conducted by looking at beams as they are warped by large galactic structures. However, smaller structures — including dark matter — can bend light as well. As a result, the team in the study used the Canada-France-Hawaii Telescope to analyze 23,000 different galaxy pairs located 4.5 billion light-years away.
This allowed them to see subtle warping amidst the galactic light. They then used that to compile a composite image of the galactic pairs that showed both the weak gravitational lensing and the presence of dark matter filaments between the galaxies.
“For decades, researchers have been predicting the existence of dark matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,” said study co-author Mike Hudson, a professor of astronomy at the University of Waterloo, in a statement. “This image moves us beyond predictions to something we can see and measure.”
This new technique could allow astronomers to view the universe in a new way and lead to further study of how different galaxies are connected. The team next plans to study more distant systems to get a better idea of the way dark matter evolved over time.
“By using this technique, we’re not only able to see that these dark matter filaments in the universe exist, we’re able to see the extent to which these filaments connect galaxies together,” said study leader Seth Epps, a graduate student at Waterloo University.