The S$^4$G-WISE View of Global Star Formation in the Nearby Universe

TL;DR

This study utilizes WISE mid-infrared data to calibrate star formation rates in nearby galaxies, improving accuracy and exploring dust properties across different galaxy morphologies.

Contribution

It presents new SFR scaling relations based on WISE data, combining W3 and W4 bands, and investigates dust and star formation in a large galaxy sample.

Findings

Combined W3 and W4 SFRs provide robust star formation estimates.

Dust density correlates with SFR deficits in low-mass galaxies.

Galaxy morphology influences dust and star formation properties.

Abstract

In this work we present source-tailored WISE mid-infrared photometry (at 3.4$\mu$m, 4.6$\mu$m, 12$\mu$m, and 23$\mu$m) of 2812 galaxies in the extended Spitzer Survey of Stellar Structure in Galaxies (S$^4$G) sample, and characterise the mid-infrared colors and dust properties of this legacy nearby galaxy data set. Informed by the relative emission between W3 (12$\mu$ m) and W4 (23$\mu$ m), we re-derive star formation rate (SFR) scaling relations calibrated to L$_{\rm TIR}$, which results in improved agreement between the two tracers. By inverse-variance weighting the W3 and W4-derived SFRs, we generate a combined mid-infrared SFR that is a broadly robust measure of star formation activity in dusty, star-forming galaxies in the nearby Universe. In addition, we investigate the use of a W3-derived dust density metric, $\Sigma_{\rm 12\mu m}$ (L$_\odot$/kpc$^2$), to estimate the SFR deficit of low mass, low dust galaxies. This is achieved by combining WISE with existing GALEX ultraviolet (UV) photometry, which we further use to explore the relationship between dust and UV emission as a function of morphology. Finally, we use our derived SFR prescriptions to examine the location of galaxies in the log SFR - log M$_\textrm{stellar}$ plane, as a function of morphological type, which underscores the complexity of dust-derived properties seen in galaxies of progressively earlier type.