Mystery of ‘extremely’ powerful cosmic ray that zapped Earth

By Stephen Beech via SWNS

The source of an "extremely" powerful cosmic ray that zapped Earth is being hunted by scientists.

The energy levels of the particle from outer space were an incredible 244 million times higher than that achieved by the most powerful accelerators ever made by humans.

The mystery particle has been named after Amaterasu - the goddess of the sun in Japanese mythology.

But, more than two years since it hit Earth, it is still not clear where it came from or even what it is, exactly.

It may sound like something out of science fiction, but Amaterasu is the subject of major research led by Japanese academic Professor Toshihiro Fujii.

He explained that cosmic rays are energetic charged particles originating from galactic and extragalactic sources.

But cosmic rays with extremely high energy are exceptionally rare; they can reach greater than 10 to the power of 18 electron volts or one extra-electron volt (EeV), which is roughly a million times higher than achieved by the most powerful accelerators ever made by humans.

Chasing after such rays from space, Professor Fujii and an international team of scientists have been conducting the Telescope Array experiment since 2008.

The specialized cosmic ray detector consists of 507 scintillator surface stations, covering a detection area of 700 square kilometers (270 sq miles) in Utah in the United States.

The research team detected a particle with a "whopping" energy level of 244 EeV on May 27, 2021.

Professor Fujii said: “When I first discovered this ultra-high-energy cosmic ray, I thought there must have been a mistake, as it showed an energy level unprecedented in the last three decades,”

He says such an energy level is only comparable to that of the most energetic cosmic ray ever observed - dubbed the “Oh-My-God” particle - which had an estimated energy of 320 EeV when detected in 1991.

Of the many candidates for the particle’s name, Fujii and his colleagues settled on “Amaterasu” after the sun goddess that, according to Shinto beliefs, was instrumental in the creation of Japan.

Fujii hopes that the Amaterasu particle will pave the way for illuminating the origins of cosmic rays.

He said: “No promising astronomical object matching the direction from which the cosmic ray arrived has been identified, suggesting possibilities of unknown astronomical phenomena and novel physical origins beyond the Standard Mode1."

Fujii added: “In the future, we commit to continue operating the Telescope Array experiment, as we embark, through our ongoing upgraded experiment with fourfold sensitivities, dubbed TAx4, and next-generation observatories, on a more detailed investigation into the source of this extremely energetic particle.”

The findings were published in the journal Science.