Mysterious Origin of Cosmic Rays Discovered: Supernovas (Video)

Where do cosmic rays come from? From the aftermath of exploding stars, of course. After a century of mystery, researchers have found evidence that supports this claim.

Cosmic rays are electrically charged particles from deep space. They usually strike Earth from every direction in space with massive amounts of energy, surpassing even the most powerful atom smashers that our planet can produce. Yet not all cosmic rays are alike. They are made up of everything from electrons to massive atomic nuclei to antimatter. However, the lion's share, 90 percent, are made up of protons.

Although scientists have long suspected that cosmic rays were products of the aftermaths of supernovas, it's only now that they've found evidence to support the speculation. Researchers spent four years analyzing gamma rays with the Large Area Telescope located onboard NASA's Fermi Gamma-ray Space Telescope. They focused on two supernova remnants located within the Milky Way: IC 433 and W44. For the first time ever, they were able to find that the sources in the universe that accelerate the protons.

The researchers examined gamma rays since they are not affected by magnetic fields and can be traced back to their sources; thus, they were perfect for studying direct evidence of cosmic ray creation. They found that shockwaves from supernovas can accelerate protons to cosmic ray energies through a process known as Fermi acceleration. This event occurs when protons get trapped by magnetic fields in the shock waves and are accelerated to near the speed of light. Collisions then occur between faster and slower protons and generate subatomic particles called neutral pions. These neutral pions then decay into gamma-ray photons, which are the most energetic form of light.

These findings could help scientists better understand the surrounding processes that occur around supernovas. Moving forward, the researchers plan to hunt for the origins of cosmic rays of even higher energy than these protons.

Their findings are published in the journal Science.

Want to see a supernova in action? Check out the video below.