Dark matter remains one of the biggest mysteries in science.
Scientists cannot see it directly, yet they believe it makes up most of the matter in the universe.
Now, a new study suggests that dark matter may gather around supermassive black holes, forming large invisible clouds that influence their surroundings.
Researchers from Virginia Tech have used a clever technique called “echo mapping” to find evidence supporting this idea. Their findings were published in the journal Physical Review D.
Astronomers have long known that something strange is happening in the universe. Stars and galaxies move much faster than expected based on the amount of visible matter they contain.
According to current understanding, the gravity from visible stars, gas, and dust is not enough to explain these high speeds.
The missing gravity is believed to come from dark matter, an invisible substance that does not emit, reflect, or absorb light. Although scientists cannot see dark matter directly, they can detect its effects through gravity.
The new study focuses on what happens near supermassive black holes, which sit at the centers of many galaxies. These black holes contain millions or even billions of times the mass of our sun and create incredibly strong gravitational fields.
Ordinary matter behaves in a predictable way around black holes. Gas, dust, and plasma collide with one another, creating friction. This causes them to lose energy and spiral inward, forming a bright structure called an accretion disk around the black hole.
Dark matter behaves very differently. Scientists believe it interacts with other matter only through gravity. Because dark matter particles do not collide and lose energy like ordinary matter, they are expected to remain farther from the black hole, forming a dense halo around it.
Testing this idea has been difficult because dark matter is invisible. However, the researchers found a way to investigate it using light echoes.
When material falls toward a black hole, it releases powerful bursts of energy that create flashes of light. These flashes travel outward and strike clouds of gas farther away. The gas absorbs the light and then emits it again, creating a delayed “echo.”
By measuring the time between the original flash and the echo, astronomers can calculate how far the gas is from the black hole. Combining this information with measurements of the black hole’s gravity allows scientists to estimate how much mass exists in the surrounding region.
The team applied this method to 14 distant galaxies. In five of them, they found evidence that the amount of mass increased with distance more quickly than visible matter alone could explain. This suggests that an additional source of mass—possibly dark matter—is present around the black holes.
The researchers stress that the results are not yet a direct detection of dark matter. Instead, they provide an important proof of concept and a promising new way to search for it.
Future observations with more powerful instruments could confirm whether these invisible halos truly exist. If they do, scientists will gain valuable new insights into both dark matter and the environments around supermassive black holes. If not, researchers may need to rethink some of their current ideas about what dark matter really is.
Either way, the study opens an exciting new path toward solving one of the universe’s greatest mysteries.
