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

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 ≤ 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 (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 1σ uncertainty down to only 0.05 dex. The apparent metallicity differences among SN types are all within ∼1σ 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.