SIMBAD references

A relationship between dust-reprocessed light from recent star formation and the amount of star-forming gas in a galaxy produces a correlation between Wide-field Infrared Survey Explorer (WISE) 12 µm emission and CO line emission. Here, we explore this correlation on kiloparsec scales with CO(1-0) maps from EDGE-CALIFA matched in resolution to WISE 12 µm images. We find strong CO-12 µm correlations within each galaxy and we show that the scatter in the global CO-12 µm correlation is largely driven by differences from galaxy to galaxy. The correlation is stronger than that between star formation rate and H₂ surface densities [Σ(H₂)]. We explore multivariable regression to predict Σ(H₂) in star-forming pixels using the WISE 12 µm data combined with global and resolved galaxy properties, and provide the fit parameters for the best estimators. We find that Σ(H₂) estimators that include Σ(12\:µm) are able to predict Σ(H₂) more accurately than estimators that include resolved optical properties instead of Σ(12\:µm). These results suggest that 12 µm emission and H₂ as traced by CO emission are physically connected at kiloparsec scales. This may be due to a connection between polycyclic aromatic hydrocarbon emission and the presence of H₂. The best single-property estimator is log(Σ(H₂)/M_☉ pc^–2) = (0.48 ±0.01) + (0.71 ±0.01) log(Σ(12 µm)/L_☉ pc^–2). This correlation can be used to efficiently estimate Σ(H₂) down to at least 1 M_☉ pc^–2 in star-forming regions within nearby galaxies.