Wednesday, August 27, 2008

All in a Gamma Ray.

Have a look at the image above; you are viewing the first map of the sky made entirely of gamma ray wavelengths! The thin golden-orange streak across what looks like a blue egg is actually gas and dust accumulated in the plane of our Milky Way. These menacing little photons, gamma rays, are the most energetic in the spectrum, and are emitted from the nucleus of certain radioactive atoms.

The gamma rays situated in the Milky Way are caused by cosmic rays, super-fast (mostly proton) particles colliding with interstellar gas. In what once took years, NASA'S Gamma-Ray Large Area Space Telescope or GLAST produced the map in just 95 hours, using LAT (Large Area Telescope), which can scan the entire sky once every 3 hours. GLAST recently got a name change too. In honor of Enrico Fermi NASA has dubbed it the new "Fermi Gamma-Ray Space Telescope".

A harbinger of high-energy physics, Fermi won the Nobel Prize in 1938 for his work on neutrons, specifically artificial radioactivity, a phenomena brought about by impinging uranium with neutrons in a non-spontaneous reaction. This contrasts with natural radioactivity, which spontaneously occurs among certain elements undergoing nuclear decay.

Scientists expect that the Fermi Telescope will continue to stack up a long list of discoveries, including more new pulsars and possibly unraveling the mysterious workings of active galaxies, whose inner cores contain super-massive black holes.

Returning to the image, the bright spot on the lower left is a blazar, while the Crab Nebula lies to the right as another bright spot. Blazars are temperamental bundles of energy fueled by super-massive black holes, they sometimes spit out streams of high-energy plasma at nearly the speed of light. The Crab Nebula is leftover supernova byproduct that contains a spinning neutron star.

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