INTEGRAL image of positron annihilation and LMXB distribution
Credit:G. Weidenspointner et al.; ESA

The Range of Annihilation

Antimatter is undoubtedly the most expensive material in the Universe. It's the propulsion system of the future that lets humankind explore the Galaxy. Its extremely deadly: combined with "normal" matter, it causes the complete annihilation of matter into energy. It exists in significant quantities in the center of the Milky Way, and in surrounding regions. The engine producing this antimatter is not known. Perhaps it's associated with supermassive black holes or tiny ones, or generated by extreme electromagnetic processes associated with ultradense dead stars. A major clue to the source of this mysterious, deadly stuff was recently identified by the INTEGRAL Gamma-Ray observatory. The instruments on INTEGRAL are sensitive to a particular type of radiation produced by the annihilation of anti-electrons (called positrons) with normal electrons. During its six-plus year mission, INTEGRAL has been observing this radiation in the Milky Way, as shown in the image above left. This image shows the distribution of annihilation radiation in Galactic coordinates, and is brightest near the center of the Galaxy where a supermassive black hole lurks. But the emission is more heavily weighted towards one side of the Galaxy. The population of low-mass X-ray binaries (LMXBs) consisting of a "normal" star paired with, and feeding material to, a neutron star is shown on the right. The population of LMXBs also shows a very similar Galactic distribution, suggesting that these LMXBs are a major source of the antimatter in the Milky Way.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:25:30 EDT