Deep within its red-hot belly, the giant red star Betelgeuse could produce tons of hypothetical dark matter particles called axions that, if they existed, would send a telltale signal. A recent search for such a tantalizing emission has deflated, but is helping physicists set new limits on the properties of the putative axion.
Betelgeuse, which appears as a bright red dot in the constellation of Orion, is a well-studied star. It is cosmologically close, only 520 light-years away Soil, and made headlines last year when it mysteriously began to dim, leading some researchers to believe it would prepare to explode like a supernova.
Being such a large and hot star, Betelgeuse may also be a perfect place to find axions, scientists say. These putative particles can have perhaps a millionth or even a billionth of the mass of an electron and are ideal candidates for making up dark matter, the mysterious substance that far outweighs the ordinary matter in the universe, but whose nature is still largely undetermined.
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As dark matter, axions shouldn’t interact much with luminous particles, but according to some theories there is a small chance that photons, or light particles, can be converted back and forth into axions in the presence of a strong magnetic field, Mengjiao Xiao, a physicist at the Massachusetts Institute of Technology (MIT) in Cambridge, told Live Science.
A star’s thermonuclear core is a good place to find large quantities of both photons and magnetism, and Betelgeuse, which has 20 times the mass of the sun, could conceivably be “what we call an axion factory,” he said.
If axions are produced in this extreme environment, they should be able to escape out and flow to Earth in great numbers. By interacting with the Milky Way’s natural magnetic field, these axions can be converted back into photons in the X-ray portion of the electromagnetic spectrum, Xiao said.
As an older star, Betelgeuse is in a phase of life where it shouldn’t be emitting much X-ray light, he added, so such radiation detected from it could indicate the presence of axions.
Xiao and his colleagues used NASA’s space-based Nuclear Spectroscopic Telescope Array (NuSTAR) to hunt for an X-ray signature from Betelgeuse, although they saw nothing beyond what was expected from common astrophysical processes, such as the small amount of X-rays that Betegeuse creates. Their findings, which Xiao will present at the April 20 The April meeting of the American Physical Society, suggest that photons and axions are at least three times less likely to interact than previously thought.
Because star environments are much noisier than conditions found in a lab, searches like these are tricky, says Joshua Foster, a physicist at MIT who was not involved in the work but who was part of an attempt to search for axions. from the star clusters near the center of our galaxy. But the team worked hard to quantify their uncertainties and helped impose new constraints on the axion’s potential properties, Foster told Live Science.
Even if researchers were to see unexpected X-rays coming from a star, it doesn’t necessarily mean axions are real. Scientists should still rule out many non-dark matter explanations for the signal before turning to new physics, Foster said.
But it’s possible that axions, if ever found, could help astronomers better understand Betelgeuse, Xiao said. If the properties of the particles were known, telescopes trained on Betelgeuse could finally pick up their signal, giving them insight into the processes taking place in its abdomen and enabling researchers to calculate when it will actually explode, he added. add to it.
Originally published on Live Science