Researchers a step closer to finding cosmic ray origins

August 30, 2013

The origin of cosmic rays in the universe has confounded scientists for decades. But a study by researchers using data from the IceCube Neutrino Observatory at the South Pole reveals new information that may help unravel the longstanding mystery of exactly how and where these "rays" (they are actually high-energy particles) are produced.

Cosmic rays can damage electronics on Earth, as well as human DNA, putting astronauts in space especially at risk.

The research, which draws on data collected by IceTop, the IceCube Observatory's surface array of detectors, is published online in Physical Review D, a leading journal in elementary particle physics.

University of Delaware physicist Bakhtiyar Ruzybayev is the study's corresponding author. UD scientists were the lead group for the construction of IceTop with support from the National Science Foundation and coordination by the project office at the University of Wisconsin, Madison.

The more scientists learn about the energy spectrum and chemical composition of cosmic rays, the closer humanity will come to uncovering where these energetic particles originate.

Cosmic rays are known to reach energies above 100 billion giga-electron volts (1011 GeV). The data reported in this latest paper cover the energy range from 1.6 times 106 GeV to 109 GeV.

Researchers are particularly interested in identifying cosmic rays in this interval because the transition from cosmic rays produced in the Milky Way Galaxy to "extragalactic" cosmic rays, produced outside our galaxy, is expected to occur in this energy range.

Exploding stars called supernovae are among the sources of cosmic rays here in the Milky Way, while distant objects such as collapsing massive stars and active galactic nuclei far from the Milky Way are believed to produce the highest energy particles in nature.

As Ruzybayev points out in a scientific figure submitted to the journal, the cosmic-ray 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 previously thought, but exhibits features 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 explained. "These measurements provide new constraints that must be satisfied by any models that try to explain the acceleration and propagation of cosmic rays."
IceTop consists of 81 stations in its final configuration, covering an area of one square kilometer on the South Pole surface above the detectors of IceCube, which are buried over a mile deep in the ice. The analysis presented in this article was performed using data taken from June 2010 to May 2011, when the array consisted of only 73 stations.

The IceCube collaboration includes nearly 250 people from 39 research institutions in 11 countries, including the University of Delaware.

University of Delaware

Related Cosmic Rays Articles from Brightsurf:

Cosmic X-rays reveal an indubitable signature of black holes
A black hole is an exotic cosmic object, from within which nothing, not even light, can escape.

Cosmic rays may soon stymie quantum computing
Infinitesimally low levels of radiation, such as from incoming cosmic rays, may soon stymie progress in quantum computing.

Using lung X-rays to diagnose COVID-19
This system uses deep learning to train a neural network model that can distinguish between healthy patients, pneumonia patients and COVID-19 patients.

How cosmic rays may have shaped life
Physicists propose that the influence of cosmic rays on early life may explain nature's preference for a uniform 'handedness' among biology's critical molecules.

Galactic cosmic rays now available for study on Earth, thanks to NASA
To better understand and mitigate the health risks faced by astronauts from exposure to space radiation, we ideally need to be able to test the effects of galactic cosmic rays (GCRs) here on Earth under laboratory conditions.

Not just for bones! X-rays can now tell us about soft tissues too
A new X-ray imaging technique could identify lesions and tumors before ultrasound or MRI can.

Galactic cosmic rays affect Titan's atmosphere
Planetary scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the secrets of the atmosphere of Titan, the largest moon of Saturn.

Invisible X-rays turn blue
A new reaction system can detect X-rays at the highest sensitivity ever recorded by using organic molecules.

Chest X-rays contain information that can be harvested with AI
The most frequently performed imaging exam in medicine, the chest X-ray, holds 'hidden' prognostic information that can be harvested with artificial intelligence (AI).

X and gamma rays --Even more powerful
International group of researchers including scientists from Skoltech have invented a new method for the generation of intense X and gamma-ray radiation based on Nonlinear Compton Scattering.

Read More: Cosmic Rays News and Cosmic Rays Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to