First results from the IllustrisTNG simulations: the galaxy colour bimodality

TLDR: The first two simulations of the IllustrisTNG project were presented in this article, focusing on the optical colors of galaxies at low redshift, and the results showed that the simulated (g-r) colors of 10^9 10^11 Msun which redden at z < 1 accumulate on average ~25% of their final z=0 mass post-reddening; at the same time, ~18% of such massive galaxies acquire half or more of their last stellar mass while on the red sequence.

Abstract: We introduce the first two simulations of the IllustrisTNG project, a next generation of cosmological magnetohydrodynamical simulations, focusing on the optical colors of galaxies. We explore TNG100, a rerun of the original Illustris box, and TNG300, which includes 2x2500^3 resolution elements in a volume twenty times larger. Here we present first results on the galaxy color bimodality at low redshift. Accounting for the attenuation of stellar light by dust, we compare the simulated (g-r) colors of 10^9 10^11 Msun which redden at z<1 accumulate on average ~25% of their final z=0 mass post-reddening; at the same time, ~18% of such massive galaxies acquire half or more of their final stellar mass while on the red sequence.