The Role of Electron Captures in Chandrasekhar Mass Models for Type Ia Supernovae

The Chandrasekhar mass model for Type Ia Supernovae (SNe Ia) has received increasing support from recent comparisons of observations with light curve predictions and modeling of synthetic spectra. It explains SN Ia events via thermonuclear explosions of accreting white dwarfs in binary stellar syste...

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Bibliographic Details
Published in:arXiv.org 2000-01
Main Authors: Brachwitz, Franziska, Dean, David J, W Raphael Hix, Iwamoto, Koichi, Langanke, Karlheinz, Martinez-Pinedo, Gabriel, Nomoto, Ken'ichi, Strayer, Michael R, Friedrich-K Thielemann, Umeda, Hideyuki
Format: Article
Language:English
Subjects:
Beta decay
Binary stars
Burning rate
Composition
Computer simulation
Constraint modelling
Deposition
Ejecta
Electron capture
Electron gas
Electrons
Ignition
Light curve
Nuclei
Stellar systems
Supernovae
Thermonuclear explosions
White dwarf stars
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Summary:The Chandrasekhar mass model for Type Ia Supernovae (SNe Ia) has received increasing support from recent comparisons of observations with light curve predictions and modeling of synthetic spectra. It explains SN Ia events via thermonuclear explosions of accreting white dwarfs in binary stellar systems, being caused by central carbon ignition when the white dwarf approaches the Chandrasekhar mass. As the electron gas in white dwarfs is degenerate, characterized by high Fermi energies for the high density regions in the center, electron capture on intermediate mass and Fe-group nuclei plays an important role in explosive burning. Electron capture affects the central electron fraction Y_e, which determines the composition of the ejecta from such explosions. Up to the present, astrophysical tabulations based on shell model matrix elements were only available for light nuclei in the sd-shell. Recently new Shell Model Monte Carlo (SMMC) and large-scale shell model diagonalization calculations have also been performed for pf-shell nuclei. These lead in general to a reduction of electron capture rates in comparison with previous, more phenomenological, approaches. Making use of these new shell model based rates, we present the first results for the composition of Fe-group nuclei produced in the central regions of SNe Ia and possible changes in the constraints on model parameters like ignition densities and burning front speeds.
ISSN:2331-8422
DOI:10.48550/arxiv.0001464