Could Dark Matter Act Like Atoms?

By Space.Fan Editorial DeskSeptember 17, 2026 at 8:00 AM UTC

Scientists used computer models to see if dark matter might behave like regular gas, changing how stars move in galaxies.

The Drop

Dark matter is a mysterious substance that makes up most of the matter in our universe, but we cannot see it because it does not give off light. Most scientists think it acts like a ghostly cloud that floats through galaxies without bumping into anything. A new study suggests a different idea: what if a small part of dark matter acts more like the atoms that make up our bodies? This is called atomic dark matter. Because atoms can bump into each other and lose energy, this type of dark matter would behave very differently than the standard version. To test this, researchers built a complex computer simulation of a galaxy similar to our own Milky Way, assuming that about 6 percent of its dark matter was this special atomic type. They watched how this changed the way groups of s, called stellar streams, moved and grew over billions of years. The team found that when they added this atomic dark matter, the galaxy formed dense pockets that helped hold satellite galaxies together. These satellite galaxies became tougher and better at surviving the pull of the main galaxy's gravity. The study also showed that these galaxies kept forming new s for a much longer time than they would have without the atomic dark matter.

Why It Matters

This study is important because it gives us a new way to look for dark matter. If dark matter can act like atoms, it leaves a fingerprint on the s we can actually see. By looking at the chemical makeup of s in these long streams, astronomers might be able to tell if our galaxy contains this hidden, atomic-like material. It helps researchers move beyond just guessing what dark matter is to predicting how it should make galaxies look.

The Catch

This finding comes from a computer simulation, which is a powerful tool but not the same as looking through a telescope. The researchers made specific assumptions about how much atomic dark matter exists, and if that percentage is wrong, the results might change. The team notes that other theories, like self-interacting dark matter, could also create similar effects in galaxies, so they cannot say for sure that atomic dark matter is the only explanation for what they see in their models.

Put That in Perspective

Scientists have studied stellar streams for years to map out the invisible gravity of our galaxy. This new work adds a deeper level of detail to those maps, focusing on how the hidden inner parts of small satellite galaxies might shape the stars around them. Future research will likely focus on comparing these model results with real data from surveys of the Milky Way to see if any stars match the chemical patterns predicted here.

Source September 17, 2026

Lucas S. Mandacarú Guerra, Stephanie O’Neil, Mariangela Lisanti, Sandip Roy, Robyn Sanderson, Aritra Kundu, Arpit Arora, Lina Necib, Nora Shipp, Xuejian Shen

Princeton University, University of Pennsylvania, Flatiron Institute, University of California San Diego, University of Washington, Massachusetts Institute of Technology·The Astrophysical Journal·10.3847/1538-4357/ae9862