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Paper: Photons and Positrons in Type Ia Supernovae
Volume: 372, 15th European Workshop on White Dwarfs
Page: 407
Authors: Hirschmann, A.; Bravo, E.; Isern, J.
Abstract: The explosion mechanisms of type Ia supernovae are still a matter of debate. These events occur when a white dwarf, belonging to a binary system, accretes enough mass from its companion star and reaches the Chandrasekhar mass limit. Many theoretical approaches have been proposed although, unfortunately, there are no observations sensitive enough to confirm or refute the various scenarios selected up to now. Hence, gamma-ray emission from these events would allow unique information on the explosion mechanisms since the high energy photons and positrons emitted are produced by the decay of radioactive elements, which in turn are generated when the incinerating front passes through the star. The properties of these radioactive elements provide robust information on the internal structure of the star and its magnetic field, and the possible reasons of the explosion, which depend on the progenitor system.

We present simulations, in the gamma-ray range, achieved by a 1D and 3D Monte Carlo code using a set of theoretical models that mimic different scenarios where we analyze the positron and photon contributions to the event by studying their transport and behavior within the expanding ejecta. For the positron transport, the positron escape fractions we obtain have been compared to those needed to explain the 511 keV positron-electron annihilation emission line seen in the Galactic Center by the INTEGRAL satellite. This comparison indicates that type Ia supernovae could possibly contribute significantly to the emission.

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