Dark matter seems to be almost a thing of science fiction rather than science. It cannot be seen, but it’s thought to make up around 85 percent of all matter in the entire universe. It’s a web that, stretching throughout space, is believed to give the actual cosmos its very structure… and yet, so far, its detection has eluded science.
This could be historic: Astronomers from Leicester University have detected a strange signal in the X-ray spectrum that appears to be a signature of ‘axions‘ — a hypothetical dark matter particle. It could take years to confirm, but this may be the first direct detection and identification of dark matter.
This discovery would completely change our understanding of how the Universe works. After all, dark matter is the force that holds our galaxies together, so learning more about it is pretty important.
The researchers first detected the signal while searching through 15 years of measurements taking by the European Space Agency’s orbiting XMM-Newton space observatory.
Unexpectedly, they noticed that the intensity of X-rays recorded by the spacecraft rose by about 10% whenever XMM-Newton was at the boundary of Earth’s magnetic field facing the Sun – even once they removed all the bright X-ray sources from the sky. Usually, that X-ray background is stable.
“The X-ray background – the sky, after the bright X-ray sources are removed – appears to be unchanged whenever you look at it,” said Andy Read, from the University of Leicester, one of the lead authors on the paper, in a press release. “However, we have discovered a seasonal signal in this X-ray background, which has no conventional explanation, but is consistent with the discovery of axions.”
Given the dearth of explanations, the researchers turned to more radical theories, including the suggestion that axions — the theoretical particles of dark matter — are streaming from the core of the Sun and producing X-rays when they smash into the Earth’s magnetic field.
According to the researchers, it’s possible that axions are produced in the core of the Sun and that they convert to X-rays in the magnetic field of the Earth. It has been suggested that the X-ray signal due to axions will be at its greatest when observered through the sunward side of the magnetic field — the place where the field is strongest.
The researchers noticed that the intensity of X-rays rose by about 10% whenever the spacecraft measured the boundary of Earth’s magnetic field that faces towards the Sun.
If these particles are indeed axions, then they must be incredibly light, featuring a mass of around a hundred billionth of an electron.
Dr. Read: “These exciting discoveries, in George’s final paper, could be truly ground-breaking, potentially opening a window to new physics, and could have huge implications, not only for our understanding of the true X-ray sky, but also for identifying the Dark Matter that dominates the mass content of the cosmos.”
President of the Royal Astronomical Society Professor Martin Barstow, who is Pro-Vice-Chancellor, Head of the College of Science & Engineering and Professor of Astrophysics & Space Science at the University of Leicester said: “This is an amazing result. If confirmed, it will be first direct detection and identification of the elusive dark matter particles and will have a fundamental impact on our theories of the Universe.”
The notion of dark matter’s existence was first proposed by Swiss astronomer Fritz Zwicky in the 1930s. For decades, scientists studying dark matter were underestimating its vast presence in the universe. It wasn’t until 2012 that a new mass-measuring technique revealed that there should be “plenty” of dark matter near the Sun.