A statistical study of the metallicity of core-collapse supernovae based on VLT/MUSE integral-field-unit spectroscopy

TL;DR

This study uses VLT/MUSE integral-field spectroscopy to analyze the metallicity of 166 core-collapse supernovae host galaxies, finding minimal differences in metallicity across SN types and suggesting other factors influence SN classification.

Contribution

It provides the largest spatially-resolved metallicity dataset for CCSN hosts from untargeted surveys, revealing that metallicity differences among SN types are statistically insignificant.

Findings

Metallicity ranges from 8.1 to 8.7 dex across SN sites.

Metallicity distributions for different SN types are statistically similar.

Uncertainty in metallicity measurements is reduced to 0.05 dex.

Abstract

Metallicity plays a crucial role in the evolution of massive stars and their final core-collapse supernova (CCSN) explosions. Integral-field-unit (IFU) spectroscopy can provide a spatially resolved view of SN host galaxies and serve as a powerful tool to study SN metallicities. While early transient surveys targeted on high star formation rate and metallicity galaxies, recent untargeted, wide-field surveys (e.g., ASAS-SN, ZTF) have discovered large numbers of SNe without this bias. In this work, we construct a large sample of SNe discovered by wide-field untargted searches, consisting of 166 SNe of Types II(P), IIn, IIb, Ib and Ic at $z \leq 0.02$ with VLT/MUSE observations. This is currently the largest CCSN sample with IFU observations. With the strong-line method, we reveal the spatially-resolved metallicity maps of the SN host galaxies and acquire accurate metallicity measurements for the SN sites, finding a range from $12 + \log(\text{O/H}) = 8.1$ to 8.7 dex. And the metallicity distributions for different SN types are very close to each other, with mean and median values of 8.4--8.5 dex. Our large sample size narrows the 1$\sigma$ uncertainty down to only 0.05 dex. The apparent metallicity differences among SN types are all within $\sim$1$\sigma$ uncertainties and the metallicity distributions for different SN types are all consistent with being randomly drawn from the same reference distribution. This suggests that metallicity plays a minor role in the origin of different CCSN types and some other metallicity-insensitive processes, such as binary interaction, dominate the distinction of CCSN types.