Image Caption: This image shows a three-color infrared view of the supernova remnant W44 (purple sphere) and surrounding regions. Credit: Herschel: Quang Nguyen Luong & F. Motte, HOBYS Key Program consortium, Herschel SPIRE/PACS/ESA consortia

 

Cosmic Rays Originate From Supernovae Shock Waves

March 1, 2013

John P. Millis, Ph.D. for redOrbit.com – Your Universe Online

As we search the heavens, one of the striking observations is that we are constantly bombarded by a stream of extremely high energy charged particles, traveling at nearly the speed of light. Known as Cosmic Rays – composed mostly (90%) of protons with the rest mostly heavy nuclei and a small number of electrons – these particles appear to come from all directions.

But where do they come from? Pinpointing this origin is a bit of a challenge. Because they are charged particles their motion is influenced by magnetic fields. And it doesn’t take the powerful fields of stars or planets to alter their trajectory, the river of magnetic field that flows throughout interstellar space can spread these particles throughout the cosmos.

Not all hope is lost however, as there are some clues to their progenitors. Being such high-energy particles, it is necessary that there be a powerful event to accelerate them to their observed velocities. Very few events have such power. This is why, for some time, researchers have looked to supernovae as the most likely candidate for their creation.

The trick is that to prove their hunch an indicator is necessary that can correlate the creation of these cosmic rays with these events. To do so, the evidence would have to come from a neutral particle – something that would not be affected by the interstellar magnetic field.

The most obvious candidate is light, specifically gamma rays – the highest form of electromagnetic radiation. When high-energy particles collide with lower energy particles (usually protons) an elementary particle known as a pion is produced. These are short lived and quickly decay into gamma rays.

Read more: Where Do Cosmic Rays Come From? – Space News – redOrbit.

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