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

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 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 untargeted searches, consisting of 161 SNe of Types II(P), IIn, IIb, Ib and Ic at $z \le 0.02$ using observations carried out by the Multi-Unit Spectroscopic Explorer on the Very Large Telescope. 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 $12 + \log (\text{O/H}) = 8.1\!-\!8.7\,\text{dex}$. Also, 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 that some other metallicity-insensitive processes, such as binary interaction, dominate the distinction of CCSN types.