Gas-phase metallicity break radii of star-forming galaxies in IllustrisTNG

ABSTRACT We present radial gas-phase metallicity profiles, gradients, and break radii at redshift z = 0–3 from the TNG50-1 star-forming galaxy population. These profiles are characterized by an emphasis on identifying steep inner gradient flat outer gradient. From this, radius, Rbreak, is defined as region where transition occurs. observe radius having a positive trend with mass that weakens redshift. When normalized stellar half-mass has weaker relation both To test if our results dependent resolution or adopted physics of TNG50-1, same analysis performed in TNG50-2 Illustris-1. find general agreement between each simulations their qualitative trends; however, TNG Illustris differ therefore breaks, size, deviate factor ∼2. In order to understand comes from, we define two relevant time-scales: enrichment time-scale gas mixing time-scale. Rbreak occurs ∼10 times long all three simulation runs, some weak dependence. This implies galactic discs can be thought two-parts: disc mixing-dominated gradient, marking them.