Is this really 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 at the University of Tokyo says he has seen at least a part of that invisible universe.

It is believed that about 68 percent of our universe is made up of dark energy, which is causing the universe to expand rapidly, and the remaining 27 percent is dark matter, which prevents galaxies from expanding.

The only problem is that we can’t see dark matter or dark energy: we only see how they interact with other objects like galaxies.

In 1933, astronomer Fritz Zwicky wondered why galaxies in a group were not blowing away from each other, based on common matter. He proposed that an invisible form of matter held them together.

Then, in the 1970s, researcher Vera Rubin also wondered why stars in spiral galaxies were held together rather than flying apart. He proposed that there was some invisible substance that prevented this from happening: dark matter.

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

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

This is not in visible light, but in gamma rays, which are 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 examine it carefully and was convinced it was correct, 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 one theory is that it’s made of something called weakly interacting massive particles, or WIMPS. These particles are heavier than protons but interact little with other matter. The idea is that when these particles collide, they will annihilate each other, releasing other particles including gamma rays.

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

Using data from Fermi, Totani claims to have captured gamma rays from the center of the galaxy.

While he has written several studies about dark matter over the past 20 years, he only started looking for gamma rays from dark matter in early 2024. This research follows on from earlier studies of gamma rays using Fermi satellite data.

“A portion of the Fermi data showed a strange excess that our model could not explain, leading me to suspect that it might be caused by radiation originating 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 match the analysis at all,” said Renée Hlozek, a cosmologist and associate professor at the Dunlop Institute for Astronomy and Astrophysics at the University of Toronto.

This is the discovery of a single author, which is rare. While Hlozek said this is “not inherently bad”, he said the paper also ignores some other analyzes that have tried to more accurately model the type of “noise” coming from our own galaxy, or the astrophysical foreground.

“So, if you’re making a big claim about detecting a dark matter signal and you either don’t cite those papers or don’t analyze the foreground really carefully, then it starts to worry me that the analysis isn’t as rigorous as the claim.”

Hlozek is not alone Questioning the claim,

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

He said, “If this radiation does indeed originate from dark matter, its scientific impact would be so tremendous that many researchers would proceed with caution in their assessments.”

“I am confident in my work, so I expect other researchers to independently analyze and confirm these results.”