Chemical evolution of disc galaxies from cosmological simulations
  We perform a suite of cosmological hydrodynamical simulations of disc
galaxies, with zoomed-in initial conditions leading to the formation of a halo
of mass $M_{\rm halo, \, DM} \simeq 2 \cdot 10^{12}$ M$_{\odot}$ at redshift
$z=0$. These simulations aim at investigating the chemical evolution and the
distribution of metals in a disc galaxy, and at quantifying the effect of $(i)$
the assumed IMF, $(ii)$ the adopted stellar yields, and $(iii)$ the impact of
binary systems originating SNe Ia on the process of chemical enrichment. We
consider either a Kroupa et al. (1993) or a more top-heavy Kroupa (2001) IMF,
two sets of stellar yields and different values for the fraction of binary
systems suitable to give rise to SNe Ia. We investigate stellar ages, SN rates,
stellar and gas metallicity gradients, and stellar $\alpha$-enhancement in
simulations, and compare predictions with observations. We find that a Kroupa
et al. (1993) IMF has to be preferred when modelling late-type galaxies in the
local universe. On the other hand, the comparison of stellar metallicity
profiles and $\alpha$-enhancement trends with observations of Milky Way stars
shows a better agreement when a Kroupa (2001) IMF is assumed. Comparing the
predicted SN rates and stellar $\alpha$-enhancement with observations supports
a value for the fraction of binary systems producing SNe Ia of $0.03$, at least
for late-type galaxies and for the considered IMFs. Adopted stellar yields are
crucial in regulating cooling and star formation, and in determining patterns
of chemical enrichment for stars, especially for those located in the galaxy
bulge.
