Empirical Dust Attenuation Model Leads to More Realistic UVJ Diagram for TNG100 Galaxies

Abstract

Dust attenuation varies substantially from galaxy to galaxy and as of yet cannot be reproduced from first principles in theoretical models. In Nagaraj et al., we developed the first Bayesian population model of dust attenuation as a function of stellar population properties and projected galaxy shape, built on spectral energy distribution fits of nearly 30,000 galaxies in the 3D-HST grism survey with broadband photometric coverage from the rest-frame UV to IR. In this paper, we apply the model, named “DustE,” to galaxies from the large-volume cosmological simulation TNG100 at z = 1. We produce a UVJ diagram and compare it with one obtained in previous work by applying approximate radiative transfer to the simulated galaxies. We find that the UVJ diagram based on our empirical model is in better agreement with observations than the previous effort, especially in the number density of dusty star-forming galaxies. We also construct the intrinsic dust-free UVJ diagram for TNG100 and 3D-HST galaxies at z ∼ 1, finding qualitative agreement but residual differences at the 10%–20% level. These differences may be caused by the finding that TNG100 galaxies have, on average, 29% younger stellar populations and possibly higher metallicities than observed galaxies.

The TNG50-SKIRT Atlas: Post-processing methodology and first data release

“…While the UVJ diagram is widely used to discriminate between star-forming and quiescent galaxies, its origin and reliability is being investigated in more detail (Belli et al 2019;Leja et al 2019;Díaz-García et al 2019;Wu et al 2020;Nagaraj et al 2022;Antwi-Danso et al 2023). More specifically, it has been investigated to which degree the UVJ colours can be used to constrain other physical properties of galaxies, and how dust attenuation affects the UVJ colours of galaxies.…”