Team member Maximiliano Bonamente, an astrophysicist and assistant professor of physics from the University of Alabama (Huntsville), states “This [discovery] means the mass of these x-ray emitting clouds is much less than we initially thought it was. A significant portion of what we thought was missing mass turns out to be these 'relativistic' electrons." [Science Daily]

The X-rays are formed, according to the UAH team, when electrons collide with photons and the energy released converts the photons from low-energy microwaves to high-energy X-rays.

At first, the team thought that low-energy (“soft”) X-rays came from warm gases and dust located within galaxy clusters, along with high-energy (“hard”) X-rays from hot gases at the center of these clusters. The mass from these warm gases and dust were thought to add about ten percent to the mass of the universe.

However, when they looked into it more, the emission lines of the soft X-rays didn’t look right. The only valid explanation was that the X-rays were created by electrons and photons, not the warm gases and dust. The team, then, concluded that the hot gases might not be the source of high-energy X-rays, which would reduce the mass of the universe even more.

Since less normal matter is out there in the universe, according to the researchers, then there is less dark matter out there, too. Dark matter was thought to exist in order to hold galaxies and galaxy clusters together. It is thought to outnumber normal matter by about five times. However, since less normal matter exists in the universe, then a relative amount of dark matter is also assumed not to be out there.
The ratio five-to-one of dark matter-to-normal matter still exists, only less of each type.

Co-authors to the article and research include Jukka Nevalainen of Helsinki Observatory and Richard Lieu of UAH.

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