EGRET/GLAST Galactic Anticenter
Credit: EGRET Team

The Gamma Ray Resolution Revolution

Gamma Ray astronomers study the most energetic radiation known in the universe. Because this radiation is so energetic, it is produced in only the most extreme of physical conditions. But these extreme physical conditions are also some of the most interesting processes that take place in the universe: black hole mergers, neutron star collapse, solar and stellar flares, and the explosive reconnection of matter and antimatter. A peculiar difficulty experienced by gamma ray astronomers is that it's impossible to focus high energy gamma rays as you can focus lower energy forms of light (like visible light, for example). This difficulty has the practical consequence that gamma ray images are vague, so that gamma ray astronomers, while they know that there is something interesting going on, often do not know where this interesting event is taking place. Recent advances have helped somewhat. The image on the left shows an image of the "Galactic Anticenter" in gamma-rays obtained by the EGRET detector on board the Compton Gamma Ray Observatory. The improved spatial resolution of EGRET allows 4 bright sources to be resolved in this image: the pulsar known as "Geminga", the Crab pulsar, and the galaxies IC 443 and PKS 0528+134. Gamma Ray imaging will greatly improve in the future with the launch of the Gamma Ray Large Area Space Telescope (GLAST), scheduled for launch in 2005. The image on the above right shows a simulation of an image by GLAST of the EGRET field. The four bright sources are easily detected, along with many more fainter sources. Identification of these faint sources will allow astronomers to understand all the various and surprising ways the universe manufactures gamma rays.

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Page Author: Dr. Michael F. Corcoran
Last modified June 14, 2001