IllustrisTNG and S2COSMOS: possible conflicts in the evolution of
  neutral gas and dust
  We investigate the evolution in galactic dust mass over cosmic time through
i) empirically derived dust masses using stacked submillimetre fluxes at 850um
in the COSMOS field, and ii) dust masses derived using a robust post-processing
method on the results from the cosmological hydrodynamical simulation
IllustrisTNG. We effectively perform a self-calibration of the dust mass
absorption coefficient by forcing the model and observations to agree at low
redshift and then compare the evolution shown by the observations with that
predicted by the model. We create dust mass functions (DMFs) based on the
IllustrisTNG simulations from 0 < z < 0.5 and compare these with previously
observed DMFs. We find a lack of evolution in the DMFs derived from the
simulations, in conflict with the rapid evolution seen in empirically derived
estimates of the low redshift DMF. Furthermore, we observe a strong evolution
in the observed mean ratio of dust mass to stellar mass of galaxies over the
redshift range 0 < z < 5, whereas the corresponding dust masses from
IllustrisTNG show relatively little evolution, even after splitting the sample
into satellites and centrals. The large discrepancy between the strong observed
evolution and the weak evolution predicted by IllustrisTNG plus post-processing
may be explained by either strong cosmic evolution in the properties of the
dust grains or limitations in the model. In the latter case, the limitation may
be connected to previous claims that the neutral gas content of galaxies does
not evolve fast enough in IllustrisTNG.
