The image above shows contours of 511 keV radiation detected by NASA's Compton Gamma Ray Observatory overlaid on an optical picture of the Galactic center. (511 keV is the energy created when a positron and an electron collide and annihilate). The vertical structure is a jet of mutually-annihilating electrons and positrons.

The discovery points to the existence of a hot fountain of gas filled with antimatter electrons rising from a region that surrounds the center of the Milky Way galaxy. The nature of the furious activity producing the hot antimatter-filled fountain is unclear, but could be related to massive star formation taking place near the large black hole at the center of the galaxy. Other possibilities include winds from giant stars or black hole antimatter factories.