The TNG50-SKIRT Atlas: Multi-wavelength nonparametric galaxy morphology

Context . Galaxy morphology is a fundamental property for describing galaxy evolution. However, the observed morphology of a particular galaxy may depend on the observed wavelength. Aims . Our aim is to investigate the wavelength dependence and the effect of dust attenuation on nonparametric morphology indicators. Methods . We used the TNG50-SKIRT Atlas, which contains synthetic UV to near-infrared broadband images for a complete stellar-mass-selected sample of 1154 galaxies extracted from the TNG50 cosmological simulation at z = 0. For each image, we calculated four nonparametric morphology indicators using the StatMorph code. Results . We find that the known correlations between stellar mass and the morphological parameters measured in the optical, together with the Gini– M 20 , concentration–Gini, and concentration– M 20 planes, are fully consistent with observational data. However, nonparametric morphological indicators change significantly with wavelength, and this wavelength dependence is stronger for disc-dominated galaxies than for bulge-dominated ones. The wavelength dependence of the morphology of our simulated TNG50 galaxies is consistent with measurements of local galaxies from the SINGS survey. We demonstrate that the effect of dust attenuation on nonparametric morphology indicators is modest across the full galaxy population, although it can be significant for individual galaxies.