The Depedence of the Star Formation Laws on Metallicity
Subhanjoy Mohanty, Jonathan Braine, Laurent Piau, Georges Helou
I will present a model which describes the regulation of the star formation efficiency in protocluster forming clumps by metallicity dependent stellar winds from the newly formed OB stars (M★ > 5 M¤). The model describes the co-evolution of the mass function of gravitationally bound cores and of the IMF in a protocluster clump. Dense cores are generated uniformly in time at different locations in the clump, and contract over lifetimes that are a few times their free-fall times. The cores collapse to form stars that power strong stellar winds whose cumulative kinetic energy evacuates the gas from the clump and quenches further core and star formation. This sets the final star formation efficiency, SFEexp. Models are run with various metallicities in the range Z/Z¤=[0.1, 2]. We find that the SFEexp decreases strongly with increasing metallicity. In the framwork of this feedback regulated mode of star formation, we construct metallicity dependent star formation laws on Galactic scales (Kennicutt-Schmidt laws) and find excellent agreement with the observations extending from low surface densities and up to the starburst regime.