Deep in the hot, hot belly, the giant red star Betelgeuse could produce tons of hypothetical dark matter particles called axons that, if they existed, would emit a revealing signal. A recent search for such a tempting show has become empty, but it is helping physicists put new limits on the properties of the supposed axion.
Appearing as a bright red dot in the constellation Orion, Betelgeuse is a well-studied star. It is cosmologically close, being only 520 light-years away Earth, and made headlines last year when it began to fade mysteriously, prompting some researchers to believe it might be preparing to explode like a supernova.
Because it is such a big, hot star, Betelgeuse could also be a perfect place to find axons, scientists say. These supposed particles could probably have a millionth or even a billionth of the mass of an electron and are ideal candidates for composing dark matter, the mysterious substance far exceeds ordinary matter in the universe, but whose nature is still largely undetermined.
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As dark matter, axons should not interact too much with light particles, but according to some theories, there is a small probability that photons or light particles can turn back and forth into axons in the presence of a strong magnetic field, Mengjiao Xiao , a physicist at the Massachusetts Institute of Technology (MIT) in Cambridge, told Live Science.
The thermonuclear core of a star is a good place to find abundant amounts of both photons and magnetism, and Betelgeuse, which is 20 times the mass of the sun, could be designed “what we call an axion factory,” he said.
If actions occur in this extreme environment, they should be able to escape and flow to Earth in large numbers. By interacting with the Milky Way galaxy’s natural magnetic field, these actions could be converted back into photons in the X-ray part of the electromagnetic spectrum, Xiao said.
As an old star, Betelgeuse is at a stage in life where it should not emit much X-ray light, he added, so that any such radiation detected in it could indicate the presence of axes.
Xiao and colleagues used the space-based telescopic nuclear spectroscopic matrix (NuSTAR) to hunt down an X-ray signature from Betelgeuse, although they saw nothing beyond what was expected from ordinary astrophysical processes, such as the amount small X-ray that Betegeuse does. Their findings, which Xiao will present on April 20 at April American Physical Society Meeting, suggests that photons and axons are at least three times less likely to interact than previously thought.
Because stellar environments are much noisier than conditions found in a laboratory, conducting such searches is difficult, said Joshua Foster, an MIT physicist who was not involved in the work but was part of a to look for axes coming from star clusters near the center of our galaxy. But the team worked hard to quantify its uncertainties and helped put new constraints on the axon’s potential properties, Foster told Live Science.
Even if researchers saw unexpected X-rays coming from a star, they would not necessarily indicate that the axes are real. Scientists should, however, rule out many explanations for matter that are not dark for the signal before resorting to new physics, Foster said.
But it is possible that the axioms, if found one day, will help astronomers better understand Betelgeuse, Xiao said. If the properties of the particles were known, the telescopes trained at Betelgeuse could eventually be able to capture their signal, providing information about the processes that take place in the stomach and allow researchers to calculate when it will actually explode, he added.
Originally published on Living science.