Dusty star-forming galaxies as tracers of protoclusters: A simulated perspective

Dusty star-forming galaxies (DSFGs) are commonly used as tracers of galaxy protoclusters, with many spectacular examples identified with telescopes such as the South Pole Telescope, Planck, and Herschel. However, to date, there has been relatively little 'first principles' theoretical work that models the connection between DSFGs and protoclusters. To address this gap, we have incorporated scaling relations (derived in previous work by performing radiative transfer calculations on hydro simulations) to predict far-IR/sub-mm flux densities into the L-Galaxies semi-analytic model. I will present a few results from this new model. Specifically, I will show that protocluster cores exhibit an excess of DSFGs relative to protocluster 'outskirts' and the field. However, contrary to some claims in the literature, this is not due to the dense environment 'triggering' starbursts, but DSFGs typically lie near the star formation main sequence. We explain this excess due to protocluster cores host more massive galaxies relative to less-overdense regions. Moreover, the model predicts that the brightest DSFGs are preferably located in protocluster cores.