Progenitor-mass-dependent yields amplify intrinsic scatter in dwarf-galaxy elemental abundance ratios
In hydrodynamic simulations, prevailing subgrid chemical-evolution models
often use a single, "IMF-averaged" supernova yield, ignoring variations in
elemental abundance ratios (particularly [$\alpha$/Fe]) in the ejecta of
higher- and lower-mass supernova progenitors within a stellar population. To
understand the impact of this simplification and understand the impact of more
explicit models, we run FIRE simulations of a dwarf galaxy $(M_\star($z = 0$)
\sim 10^6 M_\odot)$ using nucleosynthetic yields from the NuGrid database that
depend on the stellar progenitor mass and metallicity. While NuGrid exhibits
lower aggregate $\alpha$-element production than default-FIRE yields, we find
that its explicit mass dependence substantially widens the intrinsic scatter in
the simulated [Fe/H]-[$\alpha$/Fe] -- a phenomenon potentially visible in
recent observations of dwarf galaxies.