Powerful cosmic rays originate far beyond our solar system, study reports

New research from a team of international researchers could help shed light on the origin of ultra-high-energy cosmic rays.
By Clint Huston | Sep 25, 2017
The most powerful cosmic rays on record likely originate in galaxies that sit beyond the Milky Way, a new study published in the journal Science reports.

Cosmic rays -- which are particles made of numerous atomic elements -- travel through outer space at a speed approaching that of light. As a result, studying the phenomena gives researchers a way to examine matter that comes from outside our own solar system.

While many of the cosmic rays that reach Earth come from the sun, recent studies have also discovered ultra-high-energy rays that originate from somewhere in the deep reaches of space. However, while the particles are documented, researchers are not sure where they begin.

"Earth sees a constant rain of these particles, but we had no idea where they come from," study co-author Karl-Heinz Kampert, a particle astrophysicist at the University of Wuppertal in Germany, told Space.com.

The particles from such rays have so much energy that they must come from extremely-violent astrophysical phenomena. Though scientists are not sure, they postulate the rays likely originate in galaxies that have massive black holes at their centers.

To get more information on the particle's origin, a team of international researchers used the Pierre Auger Observatory to examine the electron sprays from ultra-high-energy cosmic rays between 2004 and 2016. During that time, the team looked at more than 30,000 different particles.

If the rays originated in the Milky Way they would have mostly come from the direction of the supermassive black hole that sits at the center of our galaxy. However, the ones in the study mostly came from a broad area of sky roughly 90 degrees away from the Milky Way's core. That suggests the phenomena start in nearby galaxies instead.

Though there are still many questions that need to be answered, this is the first evidence that explores the origin of ultra-high-energy cosmic rays. The team plans to expand on their study by locating the exact sources next. They hope that will give them more insight into both the particles as well as the universe's past.

"By understanding the origins of these particles, we hope to understand more about the origin of the universe, the Big Bang, how galaxies and black holes formed and things like that," said study co-author Gregory Snow, a physics professor at the University of Nebraska-Lincoln who serves as education and outreach coordinator for the Pierre Auger Observatory project, in a statement. "These are some of the most important questions in astrophysics."

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