An MIT-led look for axions from neighboring star Betelgeuse (imagined here) showed up empty, substantially narrowing the look for theoretical dark matter particle. Credit: Collage by MIT News. Betelgeuse image thanks to ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella
Search for Axions From Nearby Star Betelgeuse Comes Up Empty
Results substantially narrow the series of possible locations to discover the theoretical dark matter particles.
The evasive axion particle is lot of times lighter than an electron, with residential or commercial properties that hardly make an impression on normal matter. As such, the ghost-like particle is a leading competitor as a part of dark matter — a theoretical, undetectable kind of matter that is believed to comprise 85 percent of the mass in deep space.
Axions have actually up until now averted detection. Physicists forecast that if they do exist, they should be produced within severe environments, such as the cores of stars at the precipice of a supernova. When these stars gush axions out into deep space, the particles, on experiencing any surrounding electromagnetic fields, must quickly change into photons and possibly expose themselves.
Now, MIT physicists have actually looked for axions in Betelgeuse, a close-by star that is anticipated to stress out as a supernova quickly, a minimum of on astrophysical timescales. Given its impending death, Betelgeuse must be a natural factory of axions, continuously producing the particles as the star burns away.
However, when the group tried to find anticipated signatures of axions, in the kind of photons in the X-ray band, their search showed up empty. Their results dismiss the presence of ultralight axions that can connect with photons over a vast array of energies. The findings set brand-new restrictions on the particle’s residential or commercial properties that are 3 times more powerful than any previous laboratory-based axion-detecting experiments.
“What our results say is, if you want to look for these really light particles, which we looked for, they’re not going to talk very much to photons,” states Kerstin Perez, assistant teacher of physics at MIT. “We’re basically making everyone’s lives harder because we’re saying, ‘you’re going to have to think of something else that would give you an axion signal.’”
Perez and her coworkers have actually released their lead to Physical Review Letters. Her MIT co-authors consist of lead author Mengjiao Xiao, Brandon Roach, and Melania Nynka, in addition to 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.
A hunt for coupling
Many of the existing experiments that look for axions are created to try to find them as an item of the Primakoff impact, a procedure that explains a theoretical “coupling” in between axions and photons. Axions are not generally believed to connect with photons — for this reason their probability of being dark matter. However, the Primakoff impact forecasts that, when photons undergo extreme electromagnetic fields, such as in outstanding cores, they might change into axions. The center of lots of stars must for that reason be natural axion factories.
When a star blows up in a supernova, it needs to churn the axions out into deep space. If the undetectable particles encounter an electromagnetic field, for example in between the star and Earth, they must reverse into photons, most likely with some noticeable energy. Scientists are searching for axions through this procedure, for example from our own sun.
“But the sun also has flares and gives off X-rays all the time, and it’s hard to understand,” states Perez.
She and her coworkers rather tried to find axions from Betelgeuse, a star that generally does not release X-rays. The star is amongst those closest to Earth that are anticipated to blow up quickly.
“Betelgeuse is at a temperature and lifestage where you don’t expect to see X-rays coming out of it, through standard stellar astrophysics,” Perez describes. “But if axions do exist, and are coming out, we might see an X-ray signature. So that’s why this star is a nice object: If you see X-rays, it’s a smoking gun signal that it’s got to be axions.”
“Data are data”
The scientists tried to find X-ray signatures of axions from Betelgeuse, utilizing information taken by NuSTAR, NASA’s space-based telescope that focuses high-energy X-rays from astrophysical sources. The group acquired 50 kiloseconds of information from NuSTAR throughout the time the telescope was trained on Betelgeuse.
The scientists then designed a series of X-ray emissions that they may see from Betelgeuse if the star was gushing out axions. They thought about a series of masses that an axion may be, in addition to a series of probabilities that the axions would “couple” to and reconvert into a photon, depending upon the magnetic field strength in between the star and Earth.
“Out of all that modeling, you get a range of what your X-ray signal of axions could possibly look like,” Perez states.
When they looked for these signals in NuSTAR’s information, nevertheless, they discovered absolutely nothing above their anticipated background or beyond any normal astrophysical sources of X-rays.
“Betelgeuse is probably in the late stages of evolution and in that case should have a big probability of converting into axions,” Xiao states. “But data are data.”
Given the series of conditions they thought about, the group’s null outcome dismiss a big area of possibilities and sets a ceiling that is 3 times more powerful than previous limitations, from laboratory-based searches, for what an axion should be. In essence, this indicates that if axions are ultralight in mass, the group’s outcomes reveal that the particles should be at least 3 times less most likely to combine to photons and release any noticeable X-rays.
“If axions have ultralight masses, we can definitely tell you their coupling has to be very small, otherwise we would have seen it,” Perez states.
Ultimately, this indicates that researchers might need to aim to other, less noticeable energy bands for axion signals. However, Perez states the look for axions from Betelgeuse is not over.
“What would be exciting would be if we see a supernova, which would ignite a huge amount of axions that wouldn’t be in X-rays, but in gamma rays,” Perez states. “If a star explodes and we don’t see axions, then we’ll get really stringent constraints on an axion’s coupling to photons. So everyone’s crossing their fingers for Betelgeuse to go off.”
Reference: “Constraints on Axionlike Particles from a Hard X-Ray Observation of Betelgeuse” by Mengjiao Xiao, Kerstin M. Perez, Maurizio Giannotti, Oscar Straniero, Alessandro Mirizzi, Brian W. Grefenstette, Brandon M. Roach and Melania Nynka, 21 January 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.031101
This research study was supported, in part, by NASA.
