Type II supernovae as probes of environment metallicity: observations of host HII regions

ANDERSON; HAMUY, MARIO; STRITZINGER, MAXIMILIAN D.; BOFFIN, H. M. J.; PRIETO; GUTIÉRREZ, CLAUDIA; GALBANY; PHILLIPS; DE JAEGER; DESSART; MORRELL, N. I.; FOLATELLI, GASTÓN; KUNCARAYAKTI

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016 vol. 589 p. 110 - 129

0004-6361

Context. Spectral modelling of type II supernova atmospheres indicates a clear dependence of metal line strengths on progenitor metallicity. This dependence motivates further work to evaluate the accuracy with which these supernovae can be used as environment metallicity indicators. Aims: To assess this accuracy we present a sample of type II supernova host H ii-region spectroscopy, from which environment oxygen abundances have been derived. These environment abundances are compared to the observed strength of metal lines in supernova spectra. Methods: Combining our sample with measurements from the literature, we present oxygen abundances of 119 host H ii regions by extracting emission line fluxes and using abundance diagnostics. These abundances are then compared to equivalent widths of Fe ii 5018 Å at various time and colour epochs. Results: Our distribution of inferred type II supernova host H ii-region abundances has a range of ~0.6 dex. We confirm the dearth of type II supernovae exploding at metallicities lower than those found (on average) in the Large Magellanic Cloud. The equivalent width of Fe ii 5018 Å at 50 days post-explosion shows a statistically significant correlation with host H ii-region oxygen abundance. The strength of this correlation increases if one excludes abundance measurements derived far from supernova explosion sites. The correlation significance also increases if we only analyse a "gold" IIP sample, and if a colour epoch is used in place of time. In addition, no evidence is found of a correlation between progenitor metallicity and supernova light-curve or spectral properties - except for that stated above with respect to Fe ii 5018 Å equivalent widths - suggesting progenitor metallicity is not a driving factor in producing the diversity that is observed in our sample. Conclusions: This study provides observational evidence of the usefulness of type II supernovae as metallicity indicators. We finish with a discussion of the methodology needed to use supernova spectra as independent metallicity diagnostics throughout the Universe.