Simulating galaxy evolution with a non-universal stellar initial mass function

We consider that the stellar initial mass function (IMF) depends on physical properties of star-forming molecular clouds in galaxies and thereby investigate how such a non-universal IMF (NUIMF) influences galaxy evolution. We incorporate an NUIMF model into galaxyscale chemodynamical simulations in order to investigate the differences in chemical and dynamical evolution of disc galaxies between the NUIMF and universal IMF (UIMF) models. In the adopted NUIMF model, the three slopes of the Kroupa IMF depend independently on densities and metallicities ([Fe/H]) of molecular gas clouds, and production rates of metals and dust from massive and asymptotic giant branch stars, formation efficiencies of molecular hydrogen (H2) and feedback effects of supernovae (SNe) can vary according to the time evolution of the three IMF slopes. The preliminary results of the simulations are as follows. Star formation rates (SFRs) in actively star-forming disc galaxies can be significantly lower in the NUIMF model than in the UIMF model, and the differences between the two models can be larger in galaxies with higher SFRs. Chemical enrichment can proceed faster in the NUIMF model, and [Mg/Fe] for a given metallicity is higher in the NUIMF model. The evolution of H2 fraction (fH2 ) and dust-to-gas ratio (D) is faster in the NUIMF model so that the final fH2 and D can be higher in the NUIMF model. Formation of massive stellar clumps in gas-rich discs is more strongly suppressed owing to the stronger SN feedback effect in the NUIMF model. The radial density profiles of new stars within the central 1 kpc are shallower in the NUIMF model. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.