> More recent studies using the Telescope Array Project have suggested a source of the particles within a 20 degree radius "warm spot" in the direction of the constellation Ursa Major.
https://www.science.org/content/article/physicists-spot-pote...
https://www.science.org/content/article/physicists-spot-pote...
> Instead, theorists generally expect that the most energetic cosmic rays rev up over millions of years in unidentified accelerators the size of galaxies.
> Physicists think that the highest energy cosmic rays cannot come from more than 500 million light-years away, as interactions with lingering radiation from the big bang ought to snuff out cosmic rays from more distant sources. But no obvious candidate for a nearby cosmic accelerator lies directly in line with the hotspot, Sokolsky says. He notes, however, that in that region a filament of galaxies kinks toward Earth and speculates that magnetic fields in that string might help rev up particles.
That, or an advanced civilization. I kind of buy “high energy particles are type 1 civilizations’ pollution” more than “there exists gravitational pockets arranged in a manner capable of accelerating single protons to contain as much energy as a baseball”.