The mystery of extra-galactic rays has eluded some of the brightest minds of many a generation, over the past century. Scientists have yet to definitively pinpoint their exact source. However, using a special observatory located at the South Pole, astronomers finally believe the baffling origins of these extra-galactic rays could soon be revealed.

Cosmic rays are highly charged particles, soaring through space at extreme speeds. These rays are typically dispersed by the magnetosphere of the Earth. However, occasionally, cosmic rays are able to elude the magnetic field and collide with our planet’s atmosphere.

Extra-galactic rays are not to be confused with solar cosmic rays, which obviously stem from the sun’s chromosphere and correspond heavily with output, in the form of solar flare events.

Extra-galactic cosmic rays come from every direction of space. When cosmic rays interact with the Earth’s atmosphere they are capable of charging particles within the atmosphere. Such rays are principally composed of high-energy nuclei and positively charged protons; showers of these high energy particles are postulated to cause changes in weather pattern, provoking cloud formation, via direct collision with atmospheric particles in the troposphere.

The term ray is actually highly inaccurate, a legacy that stems from a time when scientists considered these particles to be comprised of electromagnetic radiation, instead.

But, why even bother studying these cosmic rays? Cosmic rays can present a potential threat to electronic equipment, in and around the Earth’s atmosphere. In addition to this, these high-energy particles can also harm human-beings, particularly astronauts who are not shielded by the Earth’s atmosphere.

Recent scientific conjecture, during 2009, focused upon massive supernovae as a potential source of galactic rays, based upon evidence collected by the Very Large Telescope, operated in the European Southern Observatory of northern Chile. These studies were later denounced by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), a satellite that was placed in orbit to measure highly energetic particles around the Earth’s magnetosphere. Then, PAMELA’s findings were proven to be false, during 2013, when the Farmi Gamma-ray Space Telescope collected evidence to show that some, but not all, cosmic rays result from the stellar explosions of supernovae.

Scientists working at the University of Delaware performed a series of astrological studies from the IceCube Neutrino Observatory, based at the South Pole. Here, they investigated cosmic rays between the range of 1.6 times ten to the power of six giga-electron volts (1.6*106) to ten to the power of nine giga-electron volts (109 GeV). The reason for studying cosmic rays in this region was because scientists considered this to be the energy range where Milky Way cosmic rays transition into extra-galactic cosmic rays.

The findings, which were published in the journal Physical Review D, seem to confirm that supernovae are the most common source of cosmic rays in the Milk Way. Meanwhile, collapsing stars and active galactic nuclei, which lie outside of our galaxy, are alleged to yield the particles of the highest energy.

The astronomers surmise, the more knowledge they are able to glean about the chemical constituents of the cosmic rays, the more likely they are to definitively establish where they first originated. Hopefully, the baffling mystery of these extra-galactic rays will soon be revealed after further tests have been conducted.

By: James Fenner

APS Physics Journal

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