The S4G-wise view of global star formation in the nearby universe

Abstract

In this work, we present source-tailored Wide-field Infrared Survey Explorer (WISE) mid-infrared photometry (at 3.4, 4.6, 12, and 23 μm) of 2812 galaxies in the extended Spitzer Survey of Stellar Structure in Galaxies sample, and characterize the mid-infrared colors and dust properties of this legacy nearby galaxy data set. Informed by the relative emission between W3 (12 μm) and W4 (23 μm), we rederive star formation rate (SFR) scaling relations calibrated to L 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, Σ12 μm (L ⊙/kpc2), to estimate the SFR deficit of low mass, low dust galaxies. This is achieved by combining WISE with existing Galaxy Evolution Explorer 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 stellar plane, as a function of morphological type, which underscores the complexity of dust-derived properties seen in galaxies of progressively earlier type.