Exploring the synergies of $[\mathrm{O}\mathrm{II}]\hat{I}»3727$ with MUSE spectroscopy in PHANGS H II regions

Abstract

Spatially resolved maps of gas-phase metallicity provide key constraints on the chemical enrichment and mixing processes that drive galaxy evolution, but measurements based only on strong lines remain highly uncertain and dependent on emission-line coverage. In this work, we present a joint analysis of SITELLE observations, covering the $[OII]\hat{I}»\lambda 3726,3729$ doublet, with PHANGS-MUSE spectroscopy covering 4800-9300 Angstroms, including $H{\hat{I}}^2$, $[OIII]\lambda 4959,5007$, $[NII]\lambda 6584$, $H\hat{I}\pm$, $[SII]\hat{I}»\lambda 6716,6731$, and $[SIII]\lambda 9069$, within five nearby spiral galaxies. By combining these data, we construct a homogeneous catalog of emission-line fluxes for 604 ionized nebulae, 556 of which are classified as H II regions. This enables a comparison of eight widely used strong-line metallicity calibrations, five new strong-line calibrations, and an investigation of ionization-parameter diagnostics. We recover known systematic offsets among calibrations, but also find that many exhibit very low scatter, less than 0.03-0.04 dex, in radial metallicity gradients. We find that $[SIII]/[SII]$ exhibits minimal secondary dependence on metallicity or extinction, suggesting that it may be a more robust tracer of ionization parameter than $[OIII]/[OII]$. No significant outliers are identified in O/H or N/O within the sampled regions, indicating internally consistent abundance trends across the inner disks probed by our data. We provide a publicly available catalog of all measured emission-line fluxes, designed to support future investigations, including temperature modeling and strong-line abundance calibrations.

18 pages, 11 figures. To be submitted to the Open Journal of Astrophysics