From its position deep beneath the frozen surface of Antarctica, the IceCube Neutrino Observatory, as its name implies, attempts to detect the presence of rare neutrinos amid the copious background noise of other particles known as cosmic rays. But as detailed in a paper to be published in the August 1, 2010 edition of the Astrophysical Journal Letters, scientists at the observatory began to get interested in the cosmic rays themselves when they noticed that the particles were bombarding the earth in a lopsided fashion. Reasons for the uneven pattern are still unclear, but there are some intriguing possibilities.
Too Many Cosmic Rays
In the first such measurement made from the Southern Hemisphere, scientists found that the cosmic rays hitting the earth seemed to be coming from one portion of the sky almost exclusively, rather than arriving in a more uniform pattern from all sectors of the sky as might be expected. The term for this lopsidedness is anisotropy, and though a similar phenomenon was previously observed from the Northern Hemisphere, scientists were intrigued to discover the same pattern from their base in Antarctica.
Possible Reasons for Particle Asymmetry
Researcher Rasha Abbasi of the University of Wisconsin-Madison speculated on possible scenarios that could cause the anisotropy. It could be simply an artifact of the earth's magnetic field, he said, but the more likely explanation, and one supported by many other scientists, is the presence of a supernova. A stellar explosion of this kind in the relative neighborhood of the earth could certainly account for the streams of particles emanating from one particular sector of the sky.
A Deeper Understanding of Supernovas and Cosmic Rays
When a star explodes into a supernova, an enormous amount of energy is released, causing radiation that can shine brighter than an entire galaxy. As the star explodes, it sends all of the supernova’s material flying out into space, causing a shock wave that forms a huge shell of dust and gas known as a supernova remnant.
If the supernova hypothesis turns out to be correct, scientists will have learned something significant about the source of high-energy cosmic rays. The idea that the magnetic fields contained in gases expelled by stars before they explode could act as particle accelerators, sending cosmic rays out into space at near the speed of light, could be bolstered by the findings at the IceCube Neutrino Observatory.
Source:
Moskowitz, Clara. "Antarctica Experiment Discovers Puzzling Space Ray Pattern". LiveScience. July 30, 2010
Jenny Ashford - Jenny Ashford is a writer and graphic artist from central Florida. Her main area of interest in her Suite 101 articles is science, with a ...
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