Scientists a step closer to finding cosmic ray origins

Cosmic “rays” are actually high-energy particles.

By Max Sonnenberg, The Space Reporter
Saturday, August 31, 2013

Scientists a step closer to finding cosmic ray origins

According to a news release from the University of Delaware, scientists are one step closer to finding the origin of cosmic rays. For years, this hunt has baffled scientists, but new research by scientists utilizing data from the IceCube Neutrino Observatory at the South Pole shows fresh information that may help solve the enduring puzzle of how and where these cosmic rays (or high-energy particles) are generated.

The new research is incredibly important for NASA and other space organizations, as cosmic rays are harmful to electronics on Earth, as well as human DNA, placing astronauts living or traveling in space particularly at risk.

The more scientists discover about the energy spectrum and chemical composition of cosmic rays, the closer they will come to finding the origin of cosmic rays. Cosmic rays are noted to achieve energies above 100 billion giga-electron volts. The data used in this study deals with the energy range from 1.6 times 106 GeV to 109 GeV.

Scientists are very keen on recognizing high-energy particles in this range because the changeover from cosmic rays generated in the Milky Way Galaxy to “extragalactic” cosmic rays, generated outside our galaxy, is likely to take place in this energy range.

Exploding stars known as supernovae are among the points of supply of cosmic rays here in the Milky Way, while faraway objects like collapsing massive stars and active galactic nuclei a good way from the Milky Way are thought to generate the highest energy particles in nature.

According to Bakhtiyar Ruzybayev, a University of Delaware physicist, the cosmic-ray range does not conform to a clear power law between the “knee” around 4 PeV and the “ankle” around 4 EeV, as previously believed, but displays characteristics like hardening around 20 PeV and steepening around 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,” Ruzybayev said. “These measurements provide new constraints that must be satisfied by any models that try to explain the acceleration and propagation of cosmic rays.”

The study’s findings are described in detail in the journal Physical Review D.


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