https://www.vice.com/en_us/article/5d3gq8/the-origin-of-strange-ghost-particles-from-deep-space-has-been-discovered-scientists-say

Scientists have discovered that a special type of “ghost particle” is likely forged by gargantuan black holes known as blazars, a finding that sheds light on some of the most tantalizing mysteries about our universe, such as the origin of particles called cosmic rays.

Cosmic rays are extremely energetic bits of atomic matter that shoot across space at near light speed, suggesting they hail from powerful objects that act as natural particle accelerators. One way to pinpoint sources of cosmic rays is to look for astrophysical neutrinos, another type of high-energy particle that is probably forged by the same intense mechanisms as cosmic rays.