Systematics in the Spectral Energy Distribution Fitting Parameter Estimation of Composite Galaxies

Abstract Derivation of physical properties galaxies using spectral energy distribution (SED) fitting is a powerful method, but can suffer from various systematics arising model assumptions. Previously, such biases were mostly studied in the context individual galaxies. In this study, we investigate potential performing SED on combined light two galaxies, as would be case postmerger systems. We use GALEX-SDSS-WISE Legacy Catalog z < 0.3 to identify 9000 galaxy pairs that could eventually merge. For these if UV/optical accurately determines stellar mass and (specific) star formation rate (sSFRs) pair was unresolved (merged). The sum masses (and rates (SFRs)) establishes ground truth for quantities. star-forming no (<0.1 dex) are found mass, SFR, or sSFRs. Moderate SFR (∼0.1 systems with an extreme contrast dust content between conclude arise determination SFRs account original having potentially very different histories small approach simple two-component adequate. presented flux compositing empirically determined truth, offers new opportunities testing results general.