GAMMA-RAY EMISSION FROM INDIVIDUAL CLASSICAL NOVAE

Classical novae are important producers of radioactive nuclei, such as Be-7, N-13, F-18, Na-22 and Al-26. The disintegration of these nuclei produces positrons (except for Be-7) that through annihilation with e lectrons produce photons of energies 511 keV and below. Furthermore, B e-7 and Na-22 decay producing photons with energies of 478 and 1275 ke V, respectively, well in the gamma-ray domain. Therefore, novae are po tential sources of gamma-ray emission. We have developed two codes in order to analyse carefully the gamma-ray emission of individual classi cal novae: a hydrodynamical one, which follows both the accretion and the explosion stages, and a Monte Carlo one, able to treat both produc tion and transfer of gamma-ray photons. Both codes have been coupled i n order to simulate realistic explosions. The properties of gamma-ray spectra and gamma-ray light curves (for the continuum and for the line s at 511, 478 and 1275 keV) have been analysed, with a special emphasi s on the difference between carbon-oxygen and oxygen-neon novae. Predi ctions of detectability of individual novae by the future SPI spectrom eter on board the INTEGRAL satellite are made. Concerning Al-26, its d ecay produces photons of 1809 keV but this occurs on a time-scale much longer than the typical time interval between nova outbursts in the G alaxy, making it undetectable in individual novae. The accumulated emi ssion of Al-26 from many Galactic novae has not been modelled in this paper.