Chemodynamical Simulations with Variable IMF

Using self-consistent chemodynamical simulations including star formation, supernova feedback, and chemical enrichment, I show the dependence of the initial mass function (IMF) on cosmic star formation and chemical enrichment histories. The effects of Pop-III IMF can be only seen in the elemental abundance ratios at z greater than or similar to 4 or [Fe/H] less than or similar to - 2. The preferable IMF has a flatter slope in the case of high star formation rate (SFR) and smaller upper-mass (similar to 20M(circle dot)) in the case of low SFR, which is consistent with the observed elemental abundances of dwarf spheroidal galaxies. However, the [alpha/Fe] problem of elliptical galaxies may require other solutions.