Puzzling pattern of cosmic rays in Antarctica



Puzzling pattern of cosmic rays in Antarctica Washington: An observatory still under construction in Antarctica has detected a puzzling pattern in the cosmic rays bombarding the Earth from space, a discovery scientists believe could help understand more about how these rays are formed.

Cosmic rays are highly energetic particles streaming in from space that are thought to originate in the distant remnants of dead stars. But it turns out these particles are not arriving uniformly from all directions.

A "skymap" generated from data collected by the IceCube Neutrino Observatory at the South Pole, shows that while an overabundance of cosmic rays coming from one part of the sky, a lack of such rays coming from another, LiveScience reported.

The advanced telescope, a project by the University of Wisconsin-Madison, is actually intended to detect other exotic particles called neutrinos, which are much harder to find.

But, while sifting through their cosmic-ray data to try to separate it from possible neutrino signals, the researchers noticed the intriguing pattern of cosmic rays.

"IceCube was not built to look at cosmic rays. Cosmic rays are considered background," lead researcher Rasha Abbasi of University of Wisconsin-Madison said in a statement.

"However, we have billions of events of background downward cosmic rays that ended up being very exciting."

Previous studies have found a similar lopsidedness (called anisotropy) in the sky over the Northern Hemisphere, but this was the first time scientists saw that the pattern extended to the southern sky visible from Antarctica, the scientists said.

Abbasi said: "At the beginning, we didn't know what to expect. To see this anisotropy extending to the Southern Hemisphere sky is an additional piece of the puzzle around this enigmatic effect -- whether it's due to the magnetic field surrounding us or to the effect of a nearby supernova remnant, we don't know." One idea to explain the asymmetry is that a star may have recently died in a supernova explosion relatively nearby, and its remnant may be pouring out loads of cosmic rays that would dominate the signals we receive.

Whether or not the mystery gets solved, scientists said the observations could help scientists understand more about how cosmic rays are formed in the first place.

Scientists think that the shells around dead stars, made of puffed-out layers of gas that were expelled by the star before it exploded, contain strong magnetic fields that may act as cosmic particle accelerators, speeding up particles to close to the speed of light.

"This is exciting because this effect could be the 'smoking gun' for our long-sought understanding of the source of high-energy cosmic rays," Abbasi said.

IceCube's findings on cosmic rays are detailed in the Astrophysical Journal Letters.

PTI