出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We modelled the spatial and spectral distributions of the annihilation emission induced by positrons that are released in the decay of 26Al nuclei in the Galactic disk. This was carried out through Monte Carlo simulations that take into account the propagation of positrons in the interstellar medium (ISM). The 26Al distribution was assumed to follow the free-electron spatial distribution given by Cordes & Lazio (2001). The gas distribution is based on the model given by Ferrière (1998). Due to uncertainties in the regime of positron transport in the ISM, we tested several propagation modes. When scattering off MHD waves is ignored, positrons annihilate mainly in the warm phases of the ISM, whereas they annihilate almost exclusively (96%) in the warm ionized phases when they can scatter off MHD waves. Moreover, a slight asymmetry in the 511 keV annihilation emission is observed toward negative longitudes in the two types of simulations.
