WISE band-3 luminosity (L_W3) per M_⋆ unit, as a function of sSFR for the generated library of galaxy SEDs. All panels show the same sources but in the top left they are color-coded based on their E(B − V), in the top right based on their metallicity (Z), in the bottom left on their infrared excess (IRXu = log L_W4/L_u), and in the bottom right based on their infrared excess using the g band instead of u (IRXg = log L_W4/L_g).