The annihilation of positrons with electrons in the central region of our Galaxy
results in gamma-ray line emission at 511 keV - the rest energy of the
annihilated particles. The observation of the line in 2003 shows the
ability of the SPI instrument to detect gamma-ray lines even with modest
exposures. This opens up exciting possibility for more detailed studies of
this line, since especially the Galactic Center will be observed by INTEGRAL
for much longer (e.g. as part of the Galactic Center Deep Exposure).
The spectrum shown is based on data from INTEGRAL Science Working Team (ISWT)
Core Programme data, spectra and maps for different parts of the Galactic
plane will be derived by different ISWT research groups; here we show data
from the SPI Team.
