High-resolution spectrum of the Galactic center

Recent observations of the Galactic center region indicate the presence of a narrow gamma-ray line feature at 170 keV, and theoretical speculations suggest it may result from Compton backscattering of the 511 keV annihilation radiation. The high-resolution gamma-ray spectrometer on HEAO 3 observed the Galactic center in the fall of 1979 and in the spring of 1980. In view of the recent developments, the HEAO data were re-examined to search for this new feature and to look for possible correlations with the 511 keV line emisison. No evidence for such Compton backscattered radiation was found and the derived upper limits for emission in a line feature near 170 keV were well below previously reported fluxes, indicating possible time variability.