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Compton Gamma-Ray Observatory Science Support Center

511 keV Annihilation Line Emission from Galactic Center Region


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OSSE has produced the first maps of 511 keV positron annihilation radiation from the Galactic center region. The positrons can result from the decay of radioactive elements produced in explosive objects (supernovae and novae), in energetic processes associated neutron stars and black holes, and from interactions of cosmic rays with the interstellar medium. Each of the four OSSE detectors has a 3.7o X 11.4o field-of-view, and differential observations between "source" and "background" measurements are used to map the region. Maps generated using two mapping algorithms, a Richardson-Lucy technique (top) and a singular-value-decomposition, SVD, algorithm (bottom) are shown. These maps utilize nearly all OSSE data taken in the Galactic center region, a total of 2 x 107 seconds of observing time. The emission is dominated by an intense, diffuse bulge component, emission along the Galactic plane, and with evidence for excess emission at positive Galactic latitudes. No variability of the 511 keV emission has been observed by OSSE and no discrete sources have been detected.

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This page was last modified on Monday, 01-Aug-2005 13:41:47 EDT.

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