What is known about the mysterious cosmic ray discovered in Utah that is believed to have arrived at Earth from another galaxy

A high-energy particle fell from space to the surface of the Earth in the form of lightning, but its source is not known.

This may sound like something out of science fiction, but it is a scientific fact. It’s about amaterasu, A cosmic ray fell into Utah on May 27, 2021 and has been baffling scientists ever since.

Cosmic rays, also called cosmic radiation, are subatomic particles that come from outer space and have very high energy due to their high speed.

“When I first discovered this ultra-high-energy (UHE) cosmic ray, I thought it must be a mistake, because it showed a level of energy unprecedented in the past three decades,” said Toshihiro Fujii, a researcher at Osaka Metropolitan University. University (OMU) and lead author of the study that will be published on Friday in the journal Sciences.

Extremely high-energy cosmic rays are extremely rare; It can reach more than 1,018 electron volts (the amount of kinetic energy gained or lost by one electron) or exa electron volts (EeV), which is nearly a million times more than the most powerful accelerators ever built by man. .

Amaterasu registered an energy level of 244 MeV. This energy level is similar to that of the most powerful energetic cosmic ray ever observed, nicknamed the “Oh My God” particle, which had an energy of 320 MeV when it was discovered in 1991.

To detect cosmic rays, Professor Fujii and an international team of scientists have been conducting the Telescope Array experiment since 2008.

This detector consists of 507 stations covering an area of ​​270 square miles in Utah. There, on May 27, 2021, they discovered the fall of Amaterasu.

Professor Fujii and his colleagues named the particle Amaterasu, after the sun goddess who, according to Shinto beliefs, played a crucial role in the creation of Japan.

The Amaterasu particle is perhaps as mysterious as the Japanese goddess herself. Due to the exceptionally high energy of this particle, the authors note that it should only encounter relatively small deflections by forward magnetic fields, and thus its entry path from space is expected to be closely linked to its source.

However, the results showed that its direction of arrival does not show any obvious source galaxy, nor any other known astronomical object considered as a possible source. Rather, it suggests that the particle traveled toward Earth from a vacuum in the large-scale structure of the universe, a region where there are very few galaxies.

“No astronomical object has been identified that matches the direction from which the cosmic ray arrived, suggesting possibilities for unknown astronomical phenomena and new physical origins beyond the Standard Model of particle physics,” Professor Fujii comments.

The origin of these high-energy particles mystifies scientists.

The two largest cosmic rays on record appeared “fairly random”: When their paths are traced, there doesn’t appear to be anything energetic enough to produce such particles, said John Matthews, a research professor at the University of Utah and a collaborator on the telescope array project.

The Amaterasu particle, in particular, appears to have originated in what is known as the local vacuum, an empty region of space bordering the Milky Way.

Both researchers point out that they need more data on cosmic rays of this size to be able to come up with an answer, as they currently only have information from Amaterasu and Oh-Oh-My-Gee.

Expanding the telescope array may provide some answers.

Once completed, the 500 new detectors will allow the telescope array to capture showers of particles generated by cosmic rays across about 1,120 square miles, an area about the size of Rhode Island, according to a UT statement.