Type Ia Supernovae keep memory of their progenitor metallicity

Abstract

The ultimate understanding of Type Ia Supernovae diversity is one of the most urgent issues to exploit thermonuclear explosions of accreted White Dwarfs (WDs) as cosmological yardsticks. In particular, we investigate the impact of the progenitor system metallicity on the physical and chemical properties of the WD at the explosion epoch. We analyze the evolution of CO WDs through the accretion and simmering phases by using evolutionary models based on time-dependent convective mixing and an extended nuclear network including the most important electron captures, beta decays and URCA processes. We find that, due to URCA processes and electron-captures, the neutron excess and density at which the thermal runaway occurs are substantially larger than previously claimed. Moreover, we find that the higher the progenitor metallicity, the larger the neutron excess variation during the accretion and simmering phases and the higher the central density and the convective velocity at the explosion. Hence, the simmering phase acts as an amplifier of the differences existing in SNe Ia progenitors. When applying our results to the neutron excess estimated for the Tycho and Kepler young Supernova remnants, we derive that the metallicity of the progenitors should be in the range Z=0.030-0.032, close to the average metallicity value of the thin disk of the Milky Way. As the amount of ${}^{56}$Ni produced in the explosion depends on the neutron excess and central density at the thermal runaway, our results suggest that the light curve properties depend on the progenitor metallicity.

7 pages, 3 figures, 2 tables, accepted for the publication on ApJ Letter

References in corpus (7)

• Neutronization During Type Ia Supernova Simmering
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• The Reduction of the Electron Abundance during the Pre-explosion Simmering in White Dwarf Supernovae
• Metallicity as a source of dispersion in the SNIa bolometric light curve luminosity-width relationship
• Hybrid C-O-Ne white dwarfs as progenitors of type Ia supernovae: dependence on Urca process and mixing assumptions
• A Method to Derive the Absolute Composition of the Sun, the Solar System and the Stars
• Gamow-Teller strength for the analog transitions to the first T=1/2, J^pi=3/2- states in 13C and 13N and the implications for Type Ia supernovae

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• Pre-explosive accretion and simmering phases of Type Ia Supernovae
• Synthesis of radioactive elements in novae and supernovae and their use as a diagnostic tool
• ${}^{16}O(p,\alpha {)}^{13}N$ makes explosive oxygen burning sensitive to the metallicity of the progenitors of type Ia supernovae
• Linking the properties of accreting white dwarfs with the ionization state of their ambient medium
• 3D Convective Urca Process in a Simmering White Dwarf
• Observational Properties of SNe Ia Progenitors Close to the Explosion
• On the Importance of the Convective Urca Process in 3D Simulations of a Simmering White Dwarf
• Sensitivity of 3D Convective Urca Simulations to Changes in Urca Reactions