The origin of high-energy cosmic rays may soon be revealed.
A "hotspot" of cosmic rays was detected, emanating from a patch of sky near the Big Dipper. The energy was discovered by astronomers using a network of radio telescopes, located in the desert of Utah.
Cosmic rays are the nuclei of atoms, stripped of their electron clouds. The simplest of these are single protons, which can make up the center of hydrogen atoms. These particles travel through the universe at blazing speeds. Our own sun produces cosmic rays, and the particles are also produced by some stars as they explode.
The most powerful of these rays comes from outside the Milky Way galaxy, and their origin remains a mystery.
"They have the kinetic energy of a pitched baseball. These are very high energies, much higher than can be made on Earth in any particle accelerator," Gordon Thomson, an astronomer and physicist at the University of Utah, said.
Astrophysicists are uncertain why the display occurred, but the find could help investigators learn the cause of these events, which feature the highest-energy particles in the known universe.
Supernovas, explosions created during the deaths of the most massive stars in the universe, may be the culprit behind the production of these high-energy particles. Another possibility is that supermassive black holes at the centers of galaxies could tear stars apart, creating a bean of ionized matter known as a blazar.
Earth frequently encounters cosmic rays, but nearly all of the particles are blocked by the atmosphere. An average of just over 2.5 particles reach each square mile of land every hundred years. That makes observations of the phenomenon extremely challenging.
To detect and record these particles, astronomers from the United States, Russia, Korea, Japan and Belgium created The Telescope Array. This is the largest network in the world dedicated to studying cosmic rays. The array senses particles reaching the ground, recording events occurring over roughly 300 square miles of the Utah desert. The station also records energy produced in the upper atmosphere, when cosmic rays strike a molecule in the atmosphere.
"All we see is a blob in the sky, and inside this blob there is all sorts of stuff -- various types of objects -- that could be the source [of these enigmatic rays.] Now we know where to look," Gordon Thomson, spokesman for the Telescope Array, said.
Cosmic rays were first discovered in 1912, and 90 percent of those reaching Earth are created within our own galaxy.
Research into the origin of cosmic rays will be appearing in an upcoming issue of the Astrophysical Journal Letters.
