Universe’s ‘Missing Matter’ Found By Scientists: How Did They Do It?

Two teams of researchers have solved one of the universe’s greatest mysteries, detecting the filaments that make up the universe’s “missing matter” and connect galaxies to each other.

As explained by the Daily Galaxy, previous observations hinted that galaxies and galaxy clusters only make up 10 percent of the universe’s baryon content. For years, scientists sought to find the remaining 90 percent and determine the source of the filaments that link galaxies to each other. But with the new research, scientists have finally discovered the missing half of the universe’s normal matter, meaning protons, neutrons, and electrons.

According to Popular Mechanics, two separate teams of researchers had come up with their own way to detect the universe’s missing matter, which was to look at the space between every pair of galaxies simultaneously, instead of studying the space between an individual pair of galaxies. The scientists took “hundreds of thousands” of images of galaxy pairs from the Planck satellite, and layered each image on top of each other. The images were then rotated and scaled in such a way that they lined up together.

With the images lined up, the researchers amplified the signal emerging from the filaments, turning the dim signal into something bright enough to properly analyze. This proved the theory that there are 10 times as many baryons as the ones that have already been detected. As the baryon count was high enough for them to form filaments, this effectively answered the question of where the universe’s missing matter is located, even as the filaments were still too faint to be observed with even the most powerful telescope.

“Everybody sort of knows that it has to be there, but this is the first time that somebody – two different groups, no less – has come up with a definitive detection,” said Harvard-Smithsonian Center for Astrophysics researcher Ralph Kraft in a statement.

“This goes a long way toward showing that many of our ideas of how galaxies form and how structures form over the history of the universe are pretty much correct.”

The Daily Galaxy noted that the two teams of scientists took the Sunyaev-Zel’dovich effect into account when finding the source of the universe’s missing matter. This is a phenomenon where leftover light from the Big Bang passes through hot gas, “definitively” proving that there are indeed filaments of gas in the universe. Some photons of light were shown to disperse the electrons in these filaments, resulting in a patch that was too dim for the Planck satellite to map.

Interestingly, the two teams came up with different figures for the universe’s missing matter, with one group reporting that the filaments were three times denser than the mean, and the second group observing that they were six times denser. According to Hideki Tanimura, who led one of the studies, this was to be expected, as both groups looked at the filaments at different distances.

“If this factor is included, our findings are very consistent with the other group,” said Tanimura.

[Featured Image by Egyptian Studio/Shutterstock]