Axions are a hypothetical particle that may clarify the existence of darkish matter. But it surely would possibly sometimes work together with regular matter, particularly within the cores of stars. A group of physicists have looked for proof of axions in Betelgeuse and give you nothing. It doesn’t imply that the axion doesn’t exist, but it surely does imply that it is going to be tougher to seek out.
We don’t know what the darkish matter is, which is the title we give to the element of the universe that makes up 85% of all of the mass. No matter it’s, it’s a type of particle unknown to the usual mannequin of physics. It additionally should rarely work together with photons or regular matter, in any other case we’d have seen it by now. There are lots of candidates for the darkish matter, and one household of candidate particles is known as the axions, that are predicted in varied theories of excessive power physics.
At first look the axion matches the invoice, because it’s small, light-weight, and virtually by no means interacts with gentle or regular matter. Nearly. If the axion is of a sure form generally known as “ultralight”, it might probably change into detectable by way of a course of generally known as the Primakoff impact. This impact wants a number of substances to work. If a photon is embedded in a super strong magnetic field, it might sometimes determine to show into an axion. That axion would then journey wherever it desires, because it doesn’t actually work together with anything. But when that axion encounters one other magnetic discipline, it might flip again right into a photon, normally one thing excessive power like an x-ray, giving off a flash of sunshine that betrays the existence of the axion and the Primakoff impact.
Stars have actually sturdy magnetic fields in their cores, so that they could be axion factories. And these axions could give off x-ray radiation. We’d love to make use of our solar as a laboratory for this, however sadly it’s busy releasing all kinds of x-rays for its personal causes, and so it’s exhausting to inform in the event that they’re coming from axions or one thing far much less unique.
However Betelgeuse is a distinct story. It’s an enormous star close to the tip of its life. It’s a lot cooler than the solar, so it rarely emits x-rays. So if axions exist, and the Primakoff impact is right, then Betelgeuse must be emitting a detectable quantity of x-rays.
A group of researchers based mostly on MIT did precisely that…and found squat. No x-ray. No indicators of axions.
“What our outcomes say is, if you wish to search for these actually gentle particles, which we seemed for, they’re not going to speak very a lot to photons,” says Kerstin Perez, assistant professor of physics at MIT. “We’re principally making everybody’s lives tougher as a result of we’re saying, ‘you’re going to have to consider one thing else that may offer you an axion sign.’”
These outcomes don’t rule out the existence of axions altogether. It simply signifies that in the event that they’re ultralight, then their capability to rework into photons and vice-versa needs to be very small. The truth is, these outcomes utilizing Betelgeuse alone present constraints on this ease of transition which might be thrice larger than any laboratory experiment.
So we’ll carry on searching.