A mysterious cosmic ray that was detected in Utah last year has been traced back to its source, located far outside our own Milky Way galaxy, scientists announced Monday.
The fast-moving particle, first spotted on October 17, 2020, marked the first time a cosmic ray had ever been traced back to its origin beyond the Milky Way.
The ray, detected by the Telescope Array (TA) in the western U.S. state, was traced to an active galaxy located in the constellation Bootes, 3.7 billion light-years away.
The discovery, made possible by advanced tools and methods used by researchers, could provide a better understanding of the origin of high-energy cosmic rays and their catalysts.
The team of astronomers, astrophysicians and engineers who made the discovery described the finding as a “landmark” in the field of cosmic ray research.
“This kind of analysis requires extensive data handling and astrometry, along with powerful algorithms to find the source of the particle,” said lead researcher Marcelo Alvarez-Muñiz, of the University of Chicago. “Detecting cosmic rays is the same debate as finding a needle in a haystack, but understanding the direction of the cosmic ray is like trying to find the needle in a haystack from the viewpoint of a different haystack on another continent.”
The researchers used an array of astrophysical models, sophisticated computer simulations and star catalogs to calculate the approximate location of the active galactic nucleus which produced the ray.
The ray, they determined, had been ejected by a supermassive black hole, located at the center of a distant galaxy, which had launched it in the direction of our own Milky Way.
The team also estimated that the cosmic ray had an energy of approximately 170 million times higher than that of visible light.
The discovery of the ray’s origin beyond our own galaxy was made possible, in part, thanks to the high-sensitivity particle detectors used by the Telescope Array.
The findings were published in the journal Proceedings of the National Academy of Sciences.