ar X iv : a st ro - p h / 01 07 21 6 v 1 1 2 Ju l 2 00 1 1 ANNIHILATION RADIATION IN THE GALAXY
نویسنده
چکیده
Observations of annihilation radiation in the Galaxy are briefly reviewed. We summarize astrophysical mechanisms leading to positron production and recent estimates for production rates from nova and su-pernova nucleosynthesis in the Galaxy. The physical processes involved in the production of annihilation radiation in the interstellar medium are described. These include positron thermalization, charge exchange , radiative recombination, and direct annihilation. Calculations of 2γ and 3γ spectra and the positronium (Ps) fraction due to the annihilation of positrons in media containing H and He at different temperatures and ionization states are presented. Quenching of Ps by high temperature plasmas or dust could account for differences between 0.511 MeV and 3γ Ps continuum maps. These results are presented in the context of the potential of INTEGRAL to map sites of annihilation radiation in the Galaxy. Positron production by compact objects is also considered.
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