2022MNRAS.517L..31B

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 × 10⁹ g cm^–3 for reasonable choices of accretion rate on to 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 (⁵⁴Cr) and titanium (⁵⁰Ti). We show that, in order to reconcile such a nucleosynthesis with the isotopic abundances of the Solar system, Chandrasekhar-mass WDs can account for at most 26 per cent of normal-luminosity SNe Ia, or at most 20 per cent of all SNe Ia.