An "ultra-high-energy" cosmic ray was discovered recently by scientists; this particle is the strongest since the well-known "Oh My God" particle was discovered in 1991. They are clueless as to its origin.
Scientists have observed one of the strongest cosmic rays ever recorded striking Earth, but they are unsure of the source or mechanism of the impact. According to new research, the incredibly energetic particle—named after a Japanese goddess—arrived from the direction of a void in the universe where nearly nothing is known to exist.
Protons and helium nuclei make up the majority of the extremely energetic particles known as cosmic rays, which are continuously hurled through every square inch of the universe, including our bodies. However, a subset of cosmic rays—which strike Earth about once per square mile annually—are accelerated to even higher energies by some of the most powerful phenomena in the universe.
Known as "ultra-high-energy cosmic rays," these extra-energetic particles possess at least one exa-electron volt (EeV), which is equivalent to one quintillion (1 followed by 18 zeros) electron volts. This is approximately a million times more energy than the fastest particles produced by human-made particle accelerators.
One of these supercharged cosmic rays was discovered on May 21, 2021, by scientists using the Telescope Array project, a detector consisting of separate substations spanning more than 270 square miles (700 square kilometres) in Utah. With an energy of 244 EeV, this particle is the most energetic cosmic ray since the "Oh My God" (OMG) particle, which was discovered in 1991 and had an energy of 320 EeV, travelling at a speed greater than 99.9% that of light.
A new study by Osaka Metropolitan University (OMU) researchers will be published in the journal Science on November 24. The study describes the recent cosmic ray. They dubbed the enigmatic particle "Amaterasu" in honour of the Shinto sun goddess, who is thought to have played a role in the creation of Japan.
Astrophysicist at OMU and study lead author Toshihiro Fujii said in a statement, "When I first discovered this ultra-high-energy (UHE) cosmic ray, I thought there must have been a mistake, as it showed an energy level unprecedented in the last three decades."
The precise source of the UHE ray is unknown to the scientists. The researchers stated in Science that "its arrival direction points back to a void in the large-scale structure of the Universe." There are no known nebulae, galaxies, or other cosmic structures in this area.
It's possible that magnetic fields around a star or other massive object caused the cosmic ray to be deflected towards us from its original location. But compared to their less energetic counterparts, UHE cosmic rays are less likely to be deflected, the researchers noted.
Furthermore, it is unknown what could have generated a cosmic ray with such intensity. The scientists have proposed a number of potential sources, such as pulsars, black hole mergers, and supernova explosions.
However, according to Fujii, the particle might also originate from "unknown astronomical phenomena and novel physical origins beyond the Standard Model [of physics]".
Furthermore, scientists are still unsure of the cause of the 1991 OMG particle.
The research team anticipates that next-generation observatories will be able to track these UHE particles' origins and provide light on their causes.