Is this actually the first image of dark matter?

What we see in our Universe is only about five percent of what is out there. The remaining 95 percent is invisible.

But now a researcher from the University of Tokyo says he has seen at least part of this invisible universe.

It is believed that approximately 68 percent of our Universe is made up of dark energy, which causes the Universe to expand at an increasing rate, and the remaining 27 percent is dark matter, which keeps galaxies from flying apart.

The only problem is that we can't see dark matter or dark energy: we only see how they interact with other objects, such as galaxies.

In 1933, astronomer Fritz Zwicky wondered why galaxies in a cluster were not flying away from each other, based on ordinary matter. He suggested that there was an invisible form of matter holding them together.

Then, in the 1970s, researcher Vera Rubin was also puzzled by why stars in spiral galaxies stick together rather than flying apart. She suggested that there is invisible matter that prevents this: dark matter.

Since then, scientists have been struggling to “see” dark matter in one form or another.

Now, astronomer and professor Tomonori Totani from the Department of Astronomy at the University of Tokyo says he has imaged dark matter using data from the Fermi Gamma-ray Space Telescope.

It's not about visible light, but about gamma rays, a type of radiation.

Totani said he was skeptical when he first encountered what looked like a gamma ray halo. “But when I took the time to thoroughly test it and felt confident that it was right, I got goosebumps,” he said in an email. His conclusions were published Tuesday in the Journal of Cosmology and Astroparticle Physics.

Questions remain

Astronomers don't really know what dark matter is. But there is a theory that it consists of so-called weakly interacting massive particles, or WIMPs. These particles are heavier than protons, but have very little interaction with other matter. The idea is that when these particles collide, they annihilate each other, releasing other particles, including gamma rays.

It is also believed that a good place to look for dark matter is the center of our galaxy.

Using Fermi data, Totani claims that he detected gamma rays from the center of the Milky Way.

Although he has written several studies on dark matter over the past 20 years, he only began looking for dark matter gamma rays in early 2024. The study grew out of an earlier study of gamma rays using Fermi satellite data.

“Some of the Fermi data showed a peculiar excess that our model could not explain, which led me to suspect that it might be due to radiation coming from dark matter,” Totani said.

But as the great astronomer Carl Sagan once said, extraordinary claims require extraordinary evidence.

How does it hold up?

“I think the paper—the hype around the paper—doesn't quite live up to the analysis,” said Renee Chlozek, a cosmologist and assistant professor at the Dunlap Institute of Astronomy and Astrophysics at the University of Toronto.

This is a single author find, which is rare. While Chlozek said this isn't “inherently bad,” she noted that the paper also ignores quite a few other analyzes that have tried to more accurately model the type of “noise” that comes from our own galaxy or astrophysical foreground.

“So if you make a grandiose claim about detecting a dark matter signal and don't cite those papers or do a really thorough analysis of the foreground, that's what starts to make me worry that the analysis isn't as rigorous as the claim.”

Khloshek is not the only one question a claim.

“I don't believe we have detected dark matter, but it is a very interesting and intriguing result if this analysis pans out and other researchers can reproduce the results from the data set,” Priya Natarajan, professor of physics and chair of the department of astronomy at Yale University, told CBC News via email.

While Totani is confident in his findings, he knows there is more work to be done.

“If this radiation does come from dark matter, its scientific impact would be so enormous that many researchers would likely proceed with caution in their assessments,” he said.

“I am confident in my work, so I look forward to other researchers independently analyzing and confirming these results.”