An creative making of the XMM-Newton (X-ray multi-mirror objective) area telescope. A research study of archival information from the XMM-Newton and the Chandra X-ray area telescopes discovered proof of high levels of X-ray emission from the neighboring Magnificent Seven neutron stars, which might develop from the theoretical particles called axions. Credit: D. Ducros; ESA/XMM-Newton, CC BY-SA 3.0 IGO
Researchers state they might have discovered evidence of thought axions, and perhaps dark matter, around a group of neutron stars.
A brand-new research study, led by a theoretical physicist at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), recommends that never-before-observed particles called axions might be the source of unusual, high-energy X-ray emissions surrounding a group of neutron stars.
First thought in the 1970s as part of an option to a basic particle physics issue, axions are anticipated to be produced at the core of stars, and to transform into particles of light, called photons, in the existence of an electromagnetic field.
Axions might likewise comprise dark matter — the mystical things that represents an approximated 85 percent of the overall mass of deep space, yet we have up until now just seen its gravitational impacts on regular matter. Even if the X-ray excess ends up not to be axions or dark matter, it might still expose brand-new physics.
A collection of neutron stars, called the Magnificent 7, supplied an exceptional test bed for the possible existence of axions, as these stars have effective electromagnetic fields, are fairly neighboring — within numerous light-years — and were just anticipated to produce low-energy X-rays and ultraviolet light.
“They are known to be very ‘boring,’” and in this case it’s a good idea, stated Benjamin Safdi, a Divisional Fellow in the Berkeley Lab Physics Division theory group who led a research study, released January 12 in the journal Physical Review Letters, detailing the axion description for the excess.
Christopher Dessert, a Berkeley Lab Physics Division affiliate, contributed greatly to the research study, which likewise had involvement by scientists at UC Berkeley, the University of Michigan, Princeton University, and the University of Minnesota.
If the neutron stars were of a type called pulsars, they would have an active surface area emitting radiation at various wavelengths. This radiation would appear throughout the electro-magnetic spectrum, Safdi kept in mind, and might muffle this X-ray signature that the scientists had actually discovered, or would produce radio-frequency signals. But the Magnificent 7 are not pulsars, and no such radio signal was found. Other typical astrophysical descriptions don’t appear to hold up to the observations either, Safdi stated.
If the X-ray excess found around the Magnificent 7 is created from an item or items hiding behind the neutron stars, that most likely would have appeared in the datasets that scientists are utilizing from 2 area satellites: the European Space Agency’s XMM-Newton and NASA’s Chandra X-ray telescopes.
Safdi and partners state it’s still rather possible that a brand-new, non-axion description emerges to represent the observed X-ray excess, though they stay confident that such a description will lie beyond the Standard Model of particle physics, which brand-new ground- and space-based experiments will verify the origin of the high-energy X-ray signal.
“We are pretty confident this excess exists, and very confident there’s something new among this excess,” Safdi stated. “If we were 100% sure that what we are seeing is a new particle, that would be huge. That would be revolutionary in physics.” Even if the discovery ends up not to be related to a brand-new particle or dark matter, he stated, “It would tell us so much more about our universe, and there would be a lot to learn.”
Raymond Co, a University of Minnesota postdoctoral scientist who worked together in the research study, stated, “We’re not claiming that we’ve made the discovery of the axion yet, but we’re saying that the extra X-ray photons can be explained by axions. It is an exciting discovery of the excess in the X-ray photons, and it’s an exciting possibility that’s already consistent with our interpretation of axions.”
If axions exist, they would be anticipated to act just like neutrinos in a star, as both would have really small masses and connect just really hardly ever and weakly with other matter. They might be produced in abundance in the interior of stars. Uncharged particles called neutrons move within neutron stars, periodically communicating by spreading off of one another and launching a neutrino or perhaps an axion. The neutrino-emitting procedure is the dominant manner in which neutron stars cool in time.
Like neutrinos, the axions would have the ability to take a trip beyond the star. The exceptionally strong electromagnetic field surrounding the Magnificent 7 stars — billions of times more powerful than electromagnetic fields that can be produced on Earth — might trigger leaving axions to transform into light.
Neutron stars are exceptionally unique items, and Safdi kept in mind that a great deal of modeling, information analysis, and theoretical work entered into the most recent research study. Researchers have actually greatly utilized a bank of supercomputers called the Lawrencium Cluster at Berkeley Lab in the most recent work.
Some of this work had actually been carried out at the University of Michigan, where Safdi formerly worked. “Without the high-performance supercomputing work at Michigan and Berkeley, none of this would have been possible,” he stated.
“There is a great deal of information processing and information analysis that entered into this. You need to design the interior of a neutron star in order to forecast the number of axions need to be produced within that star.”
Safdi kept in mind that as a next action in this research study, white dwarf stars would be a prime location to look for axions due to the fact that they likewise have really strong electromagnetic fields, and are anticipated to be “X-ray-free environments.”
“This starts to be pretty compelling that this is something beyond the Standard Model if we see an X-ray excess there, too,” he stated.
Researchers might likewise employ another X-ray area telescope, called NuStar, to assist fix the X-ray excess secret.
Safdi stated he is likewise thrilled about ground-based experiments such as CAST at CERN, which runs as a solar telescope to find axions transformed into X-rays by a strong magnet, and ALPS II in Germany, which would utilize an effective electromagnetic field to trigger axions to change into particles of light on one side of a barrier as laser light strikes the opposite of the barrier.
Axions have actually gotten more attention as a succession of experiments has actually stopped working to show up indications of the SISSY (weakly communicating enormous particle), another appealing dark matter prospect. And the axion photo is not so simple — it might in fact be a household album.
There might be numerous axion-like particles, or ALPs, that comprise dark matter, and string theory — a prospect theory for explaining the forces of deep space — holds open the possible presence of numerous kinds of ALPs.
Reference: “Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars” by Malte Buschmann, Raymond T. Co, Christopher Dessert and Benjamin R. Safdi, 12 January 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.021102
The research study was supported by the U.S. Department of Energy Office of Science Early Career Research Program; Advanced Research Computing and the Leinweber Graduate Fellowship at the University of Michigan, Ann Arbor; the National Science Foundation; the Mainz Institute for Theoretical Physics (MITP) of the Cluster of Excellence PRISMA+; the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG Excellence Cluster Origins; and the CERN Theory department.
