Scientists Step Closer To Finding Cosmic Ray Origin; New Concepts Of 'Hardening' And 'Steepening' Revealed
Aug 31, 2013 12:34 PM EDT
Scientists have been puzzling over the origin of cosmic rays for decades, but they may have gotten a step closer.
The "rays" are actually high-energy particles that can damage human DNA, putting astronauts at risk, a University of Delaware press release reported. The mysterious particles can also interfere with Earthly electronics.
Exploding supernovae stars are usually the source of these rays in our galaxy. "Collapsing massive stars and active galactic nuclei" are what forms the most powerful rays in far-off space.
The research team looked at rays within the energy range that characterizes the transition from the milder cosmic rays produced in the Milky Way to "extragalactic" cosmic rays produced light-years away.
In 2009, researchers discovered the cosmic rays had reached "an all time high," a NASA press release reported.
"In 2009, cosmic ray intensities have increased 19 percent beyond anything we've seen in the past 50 years," Richard Mewaldt of Caltech, said. "The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions."
Researchers hope to learn more about the rays so as to better protect astronauts journeying through space. Through the study, the team was able to debunk an old theory.
The energy spectrum does not "follow a simple power law between the "knee" around 4 PeV (peta-electron volts) and the "ankle" around 4 EeV (exa-electron volts)," as was the pas theory, the press release reported. Instead it is believed to harden at 20 PeV, and steepen at about 130 PeV.
"The spectrum steepens at the 'knee,' which is generally interpreted as the beginning of the end of the galactic population. Below the knee, cosmic rays are galactic in origin, while above that energy, particles from more distant regions in our universe become more and more likely," University of Delaware physicist Bakhtiyar Ruzybayev, an author of the study, said.
"Measurements provide new constraints that must be satisfied by any models that try to explain the acceleration and propagation of cosmic rays," he said.