Abstract
Context. Although the question of progenitor systems and detailed
explosion mechanisms still remains a matter of discussion, it is
commonly believed that Type Ia supernovae (SNe Ia) are production sites
of large amounts of radioactive nuclei. Even though the gamma-ray
emission due to radioactive decays is responsible for powering the light
curves of SNe Ia, gamma rays themselves are of particular interest as a
diagnostic tool because they directly lead to deeper insight into the
nucleosynthesis and the kinematics of these explosion events.
Aims: We study the evolution of gamma-ray line and continuum emission of
SNe Ia with the objective of analyzing the relevance of observations in
this energy range. We seek to investigate the chances for the success of
future MeV missions regarding their capabilities for constraining the
intrinsic properties and the physical processes of SNe Ia.
Methods: Focusing on two of the most broadly discussed SN Ia progenitor
scenarios - a delayed detonation in a Chandrasekhar-mass white dwarf
(WD) and a violent merger of two WDs - we used three-dimensional
explosion models and performed radiative transfer simulations to obtain
synthetic gamma-ray spectra. Both chosen models produce the same mass of
56Ni and have similar optical properties that are in
reasonable agreement with the recently observed supernova SN 2011fe. We
examine the gamma-ray spectra with respect to their distinct features
and draw connections to certain characteristics of the explosion models.
Applying diagnostics, such as line and hardness ratios, the detection
prospects for future gamma-ray missions with higher sensitivities in the
MeV energy range are discussed. Results: In contrast to the
optical regime, the gamma-ray emission of our two chosen models proves
to be quite different. The almost direct connection of the emission of
gamma rays to fundamental physical processes occurring in SNe Ia permits
additional constraints concerning several explosion model properties
that are not easily accessible within other wavelength ranges. Proposed
future MeV missions such as GRIPS will resolve all spectral details only
for nearby SNe Ia, but hardness ratio and light curve measurements still
allow for a distinction of the two different models at 10 Mpc and 16 Mpc
for an exposure time of 106 s. The possibility of detecting
the strongest line features up to the Virgo distance will offer the
opportunity to build up a first sample of SN Ia detections in the
gamma-ray energy range and underlines the importance of future space
observatories for MeV gamma rays.
Original language | English |
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Journal | Astronomy & Astrophysics |
Volume | 554 |
Publication status | Published - 01 Jun 2013 |
Keywords
- supernovae: general
- hydrodynamics
- nuclear reactions
- nucleosynthesis
- abundances
- radiative transfer
- gamma rays: general
- line: formation