Simulating a metallicity-dependent initial mass function: Consequences
  for feedback and chemical abundances
  Observational and theoretical arguments increasingly suggest that the initial
mass function (IMF) of stars may depend systematically on environment, yet most
galaxy formation models to date assume a universal IMF. Here we investigate
simulations of the formation of Milky Way analogues run with an empirically
derived metallicity-dependent IMF and the moving-mesh code AREPO in order to
characterize the associated uncertainties. In particular, we compare a constant
Chabrier and a varying metallicity-dependent IMF in cosmological,
magneto-hydrodynamical zoom-in simulations of Milky Way-sized halos. We find
that the non-linear effects due to IMF variations typically have a limited
impact on the morphology and the star formation histories of the formed
galaxies. Our results support the view that constraints on stellar-to-halo mass
ratios, feedback strength, metallicity evolution and metallicity distributions
are in part degenerate with the effects of a non-universal,
metallicity-dependent IMF. Interestingly, the empirical relation we use between
metallicity and the high mass slope of the IMF does not aid in the quenching
process. It actually produces up to a factor of 2-3 more stellar mass if
feedback is kept constant. Additionally, the enrichment history and the z = 0
metallicity distribution are significantly affected. In particular, the alpha
enhancement pattern shows a steeper dependence on iron abundance in the
metallicity-dependent model, in better agreement with observational
constraints.
