Tracing the History of Obscured Star Formation with Cosmological Galaxy Evolution Simulations

We explore the cosmic evolution of the fraction of dust obscured star formation predicted by the \textsc{simba} cosmological hydrodynamic simulations featuring an on-the-fly model for dust formation, evolution, and destruction. We find that up to $z=2$, our results are broadly consistent with previous observational results of little to no evolution in obscured star formation. However, at $z>2$ we find strong evolution at fixed galaxy stellar mass towards greater amounts of obscured star formation. We explain the trend of increasing obscuration at higher redshifts by greater typical dust column densities along the line of sight to young stars. We additionally see that at a fixed redshift, more massive galaxies have a higher fraction of their star formation obscured, which is explained by increased dust mass fractions at higher stellar masses. Finally, we estimate the contribution of dust-obscured star formation to the total star formation rate budget and find that the dust obscured star formation history (SFH) peaks around $z\sim 2-3$, and becomes subdominant at $z\gtrsim 5$.