Sensitivity of Type Ia supernovae to electron capture rates

Abstract

The thermonuclear explosion of massive white dwarfs is believed to explain at least a fraction of Type Ia supernovae (SNIa). After thermal runaway, electron captures on the ashes left behind by the burning front determine a loss of pressure, which impacts the dynamics of the explosion and the neutron excess of matter. Indeed, overproduction of neutron-rich species such as ${}^{54}$Cr has been deemed a problem of Chandrasekhar-mass models of SNIa for a long time. I present the results of a sensitivity study of SNIa models to the rates of weak interactions, which have been incorporated directly into the hydrodynamic explosion code. The weak rates have been scaled up/down by a factor ten, either globally for a common bibliographical source, or individually for selected isotopes. In line with previous works, the impact of weak rates uncertainties on sub-Chandrasekhar models of SNIa is almost negligible. The impact on the dynamics of Chandrasekhar-mass models and on the yield of ${}^{56}$Ni is also scarce. The strongest effect is found on the nucleosynthesis of neutron-rich nuclei, such as ${}^{48}$Ca, ${}^{54}$Cr, ${}^{58}$Fe, and ${}^{64}$Ni. The species with the highest influence on nucleosynthesis do not coincide with the isotopes that contribute most to the neutronization of matter. Among the last ones, there are protons, ${}^{54,55}$Fe, ${}^{55}$Co, and ${}^{56}$Ni, while the main influencers are ${}^{54,55}$Mn and ${}^{55-57}$Fe, in disagreement with Parikh et al (2013), who found that SNIa nucleosynthesis is most sensitive to the ${\beta }^{+}$-decay rates of ${}^{28}$Si, ${}^{32}$S, and ${}^{36}$Ar. An eventual increase in all weak rates on pf-shell nuclei would affect the dynamical evolution of hot bubbles, running away at the beginning of the explosion, and the yields of SNIa.

accepted for Astronomy and Astrophysics

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• The Late-Time Light Curves of Type Ia Supernovae: Confronting Models with Observations
• Type Ia Supernova Nucleosynthesis: Metallicity-Dependent Yields
• Finite-temperature electron-capture rates for neutron-rich nuclei around N=50 and effects on core-collapse supernovae simulations
• Thermonuclear and Electron-Capture Supernovae from Stripped-Envelope Stars
• Chandrasekhar-mass white dwarfs are the progenitors of a small fraction of Type Ia supernovae according to nucleosythesis constraints
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