Testing the effect of the progenitor metallicity on the ⁵⁶ Ni mass and constraining the progenitor scenarios in Type Ia supernovae

The analytical model found that the intrinsic variation in the initial metallicity of the Type Ia supernova (SN Ia) progenitor stars ( Z progenitor ) translates into a 25% variation in the synthesized 56 Ni mass, and therefore, into a difference of ∼0.2 mag in the observed peak luminosity of SNe Ia. Previous observational studies used the currently observed global gas-phase metallicity of host galaxies, instead of Z progenitor that was used in the model, and the studies showed a higher scatter in the 56 Ni mass measurements than the model prediction. We used Z progenitor of 34 normal SNe Ia and employed recent SN Ia explosion models with various configurations to cover the observed 56 Ni mass range. Unlike previous studies, which only used samples in the sub-solar range, our sample covers the Z progenitor range (1/3 Z ⊙ < Z progenitor < 3 Z ⊙ ), where most of the Z progenitor effect occurs. Linear regression returns a slope of 0.02 ± 0.03, which trend is opposite to that of the analytical model, but at at low statistical significance level. A comparison of our sample with SN Ia explosion models on the Z progenitor – 56 Ni mass diagram allowed us to constrain the progenitor scenarios. We also explored other chemical composition indicators, such as (Fe/H) progenitor and ( α /Fe) progenitor . For (Fe/H) progenitor , our sample follows the trend predicted by the analytical models, but at a low significance level (0.4 σ ). Noticeably, ( α /Fe) progenitor shows the opposite trend and a clear gap. When we split the sample at ( α /Fe) progenitor = 0.35( α /Fe) ⊙ , we find a 3 σ difference in the weighted means of the 56 Ni mass. Lastly, the standardized luminosities of SNe Ia in different Z progenitor groups differed by 0.14 ± 0.09 (1.6 σ ) mag. We highlight a holistic approach (from the progenitor star to the explosion with SN Ia and host galaxy observational data) to understanding the underlying physics of SNe Ia for a more accurate and precise cosmology.