Application of the two-component dust attenuation toy model to a single TNG100 galaxy (subhalo ID: 63990, M_⋆ ≈ 10^11.2 M_⊙, SFR ≈ 140 M_⊙yr⁻¹). Shown are the V − J color (upper panel), U − V color (center panel), and V-band attenuation (lower panel) as a function of the two parameters of the toy model: t_split, which denotes the age up to which stellar populations are attenuated, and τ_V^screen, which denotes the V-band optical depth of the dust screens. The black dots mark the (t_split, τ_V^screen) combinations that we selected to visualize in Fig. 9. To reach the very red V − J colors observed for massive, star-forming galaxies, the stellar populations of this TNG100 galaxy need to be dust-obscured at least up to t_⋆ ∼ 1 Gyr.

Fig. 9.

Results of our toy model for TNG100 galaxies with two-component dust attenuation. We show the UVJ diagram of massive, star-forming TNG100 galaxies for various combinations of the free parameters t_split and τ_V^screen in our toy model. The color-coding corresponds to the V-band attenuation for the TNG100 galaxies. We show the observational JWST/NIRCam data for massive (M_⋆ > 10¹¹ M_⊙) galaxies as grey contours. The toy model in the center of the figure with dust screns of intermediate optical depths (τ_V^screen ≈ 3.2) covering all stellar populations up to an age of t_split = 1.6 Gyr provides the best match to the observational constraints.