Chandrasekhar-mass white dwarfs are the progenitors of a small fraction of Type Ia supernovae according to nucleosythesis constraints

TL;DR

This study uses nucleosynthesis constraints and explosion simulations to show that Chandrasekhar-mass white dwarfs can only account for a small fraction of Type Ia supernovae, specifically up to 26%.

Contribution

It provides new nucleosynthesis-based constraints on the progenitor mass of Type Ia supernovae, emphasizing the limited role of Chandrasekhar-mass white dwarfs.

Findings

Chandrasekhar-mass WDs produce neutron-rich isotopes like $^{54}$Cr and $^{50}$Ti.

Such WDs can explain at most 26% of normal-luminosity SNe Ia.

Chandrasekhar-mass progenitors are unlikely to account for all SNe Ia.

Abstract

The precise progenitor system of type Ia supernovae (SNe Ia), whether it is a white dwarf (WD) close to the Chandrasekhar limit or substantially less massive, has been a matter of debate for decades. Recent research by our group on the accretion and simmering phases preceding the explosion of a massive WD has shown that the central density at thermal runaway lies in the range $(3.6-6.3)\times10^9$ g cm$^{-3}$ for reasonable choices of accretion rate onto the WD and progenitor metallicity. In this work, we have computed one-dimensional simulations of the explosion of such WDs, with special emphasis on the chemical composition of the ejecta, which in all cases is extremely rich in neutronized isotopes of chromium ($^{54}$Cr) and titanium ($^{50}$Ti). We show that, in order to reconcile such a nucleosynthesis with the isotopic abundances of the Solar System, Chandrasekhar-mass white dwarfs can account for at most 26 per cent of normal-luminosity SNe Ia, or at most 20 per cent of all SNe Ia.