The accessible axion element is many times lighter than an electron, with properties that largely affect a conventional object. The ghost-like part is therefore a major competitor as part of a dark matter – a kind of hypothetical, invisible thought that is thought to make up 85 percent of the mass in the universe .
So far Axions has avoided detection. Physicists argue that, if they exist, they must be extracted in extreme environments, such as the heart of the stars at the edge of a supernova. When these stars emit axions out into the universe, the particles, when they encounter magnetic fields around them, should move briefly into photons and may manifest themselves. .
Now, MIT physics experts have discovered axions in Betelgeuse, a nearby star that is expected to fire out as a supernova soon, at least on celestial timeframes. As it nears decay, Betelgeuse should be a natural factory of axions, churning out the grains as the star burns away.
However, when the team looked for signatures of expected axions, in the form of photons in the X-ray band, their search became empty. Their results govern the existence of ultralight axions that can interact with photons over a wide range of energy. The findings place new limitations on boy traits that are three times stronger than any laboratory-based detection-axion tests.
“What our results say is, if you want to look for those light grains, which we’ve observed, they’re not going to talk much about photons,” said Kerstin Perez, vice president. professor of physics at MIT. “We’re basically making everyone’s life more difficult because we’re saying, ‘you have to think of something else that would give you an ax signal.'”
Perez and her colleagues have published their findings today in Corporate Review Letters. Her MIT co-authors include lead author Mengjiao Xiao, Brandon Roach, and Melaina Nynka, along with Maurizio Giannotti of Barry University, Oscar Straniero of the Abruzzo Astronomical Observatory, Alessandro Mirizzi of the National Institute for Nuclear Physics in Italy, and Brian Grefenstette of Caltech.
Hunt for a connection
Many of the standard experiments that detect axions are designed to look for them because of the influence of Primakoff, a process that describes a theoretical “connection” between axions and photons. Axions are not usually thought to interact with photons – so they tend to be dark cases. However, Primakoff’s effect suggests that, when photons are subjected to intense magnetic fields, such as in stellar corrugations, they can turn into axions. So the center of many stars should be natural axion factors.
When a star explodes in a supernova, it should bury the axions out into the universe. If the invisible particles run into a magnetic field, for example between the star and Earth, they should turn back into photons, perhaps with some recognizable energy. Scientists hunt for axions through this process, for example from our own sun.
“But the sun also has flames and will emit X-rays all the time, which is hard to understand,” Perez says. Instead she and her colleagues watched Axions from Betelgeuse, a star that doesn’t usually emit X-rays. The star is among those closest to Earth that is expected to explode soon.
“Betelgeuse has a temperature and a lifestyle where you don’t expect to see X-rays coming out of it, through stellar conventional astronauts,” Perez explains. “But if there are axions, and they come out, we might see an X-ray signature. So that’s why this star is a nice thing: If you see X -rays, it is a sign of a smoke gun that the axions must be. ”
“Data is data”
The researchers were looking for X-ray signatures of axions from Betelgeuse, using data provided by NuSTAR, a NASA space-based telescope that targets full-energy X-rays from astrophysical sources . The team received 50 kiloseconds of data from NuSTAR during the time the telescope was training on Betelgeuse.
The researchers then described a range of X-ray emissions that they would see from Betelgeuse if the star sputtered out axions. They considered an area of potential mass of an axion, as well as a range of probabilities that the axions would “pair” and revert to a photon, depending on the strength of the magnetic field between the star and the Earth.
“Out of all those modeling, you get a range of possible looks at your X-ray signal of axions,” Perez says.
When searching for these signals in NuSTAR data, however, they found nothing above the expected background or outside of conventional celestial sources of X-rays.
“Betelgeuse is probably in the late stages of evolution and in that case there should be a high probability of turning to axions,” Xiao says. “But data is data.”
Given the range of scenarios they considered, the team’s null result manages a wide range of possibilities and sets an upper limit that is three times stronger than previous boundaries, from laboratory-based investigations, to what an ax must be. In fact, this means that if there are ultralight axions in mass, the team’s findings show that the particles must be at least three times more likely to pair for photons and so-called X-ray scattering. known.
“If axions have ultralight masses, we can definitely tell you that their connection must be very small, otherwise we would have seen it,” Perez says.
Ultimately, this means that scientists may need to look at other less easily detected energy bands for axion signals. However, Perez says the search for axions from Betelgeuse is not over.
“What would be interesting is if we see a supernova, which would light a lot of axes not in X-rays, but in gamma rays,” Perez says. “If a star explodes and we don’t see axions, we get tight restrictions on axion attachment to photons. So everyone crosses their fingers for Betelgeuse to go off.”
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This research was supported, in part, by NASA.
Written by Jennifer Chu, MIT Press Office