Something out in space has been bombarding Earth with incredibly high energy particles called cosmic rays. The origin of cosmic rays has been a mystery since their discovery over a century ago.
But twelve years of data from an unusual observatory in South America has now confirmed that cosmic rays with the highest energies come from sources outside the Milky Way. In particular, the majority of the high-energy particles originate from an area of the sky that lies almost opposite from the center of our own galaxy, in a region of space with a high concentration of other galaxies.
“The distribution of arrival directions of the highest energy cosmic ray particles has an enhancement in a broad patch of the sky which is roughly 120 degrees away from a line pointing from Earth to the center of our Milky Way galaxy, meaning cosmic rays coming to the Earth from that patch must be coming from other galaxies,” Gregory Snow, a physics professor from the University of Nebraska-Lincoln, said in an email to Seeker. He is also the education and outreach coordinator for the Pierre Auger Observatory, which is located in western Argentina and was the source of the data.
Snow and a group of more than 400 scientists from 18 countries published last week their analysis of cosmic rays in the journal Science.
He explained the direction of the enhanced patch is consistent with a region of galaxies that is more dense than other regions of the sky.
Read more: https://www.seeker.com/space/astrophysics/cosmic-rays-originate-far-beyond-the-milky-way