In the 1970s, scientists theorized the existence of axions: particles born in the hearts of stars that, when exposed to a magnetic field, become light particles, and which may even comprise dark matter. To date, however, axions have not been observed, miring them in the realm of the theoretical. Now, a series of mysterious X-ray emissions – and a blast of supercomputing power – suggest that we may be about to learn more about the elusive particles.
The Magnificent 7 are a group of neutron stars hundreds of parsecs from Earth. The Magnificent 7, which have strong magnetic fields, are surrounded by high-energy X-ray emissions – but since researchers wouldn’t expect those emissions from neutron stars, and other explanations came up short. So the MIT researchers started looking for signs of axions around the Magnificent 7.
“We are pretty confident this excess exists, and very confident there’s something new among this excess,” said Benjamin Safdi, the divisional fellow in Berkeley Lab’s Physics Division theory group who led the study, in an interview with Berkeley Lab’s Glenn Roberts Jr. “If we were 100% sure that what we are seeing is a new particle, that would be huge. That would be revolutionary in physics.”
The study details how axions could explain the X-ray emissions, with the theory stemming from heavy-duty data analytics work that was enabled by supercomputers. Specifically, the researchers used Berkeley Lab’s Lawrencium Cluster, a 942-node bank of cluster pools powered by a medley of Intel CPUs, Nvidia GPUs, and InfiniBand networking. The team also used HPC resources at the University of Michigan.
“Without the high-performance supercomputing work at Michigan and Berkeley, none of this would have been possible,” Safdi said. “There is a lot of data processing and data analysis that went into this. You have to model the interior of a neutron star in order to predict how many axions should be produced inside of that star.”
The researchers are excited about their results, but they’re not claiming victory in the hunt for the axion – at least, not right now.
“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,” said Raymond Co, a postdoctoral researcher at the University of Minnesota. “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.”
Next, Safdi says, they might search for axions in white dwarf stars, which would otherwise not be expected to emit X-rays.