Galactic 1.275-MeV emission from ONe novae and its detectability by INTERGRAL/SPI

Models of Galactic 1.275-MeV emission produced by the decay of the radionuc lide Na-22 have been computed. Several frequency-spatial distributions of n ovae have been investigated using recent results of nova rates and spatial distributions of novae in our Galaxy. These models allow us to estimate the lower limit of the Na-22 mass ejected per ONe nova detectable with the fut ure spectrometer (SPI) of the INTEGRAL observatory as a function of the fre quency-spatial distribution of ONe novae in the Galaxy. Calculations using recent estimations of the expected Na-22 mass ejected per ONe nova show tha t the detection of the Galactic emission of 1,275-MeV photons will be diffi cult with the future spectrometer of the INTEGRAL observatory, whereas the cumulative emission around the Galactic Centre has some chance of being det ected during the deep survey of the central radian of the Galaxy.