Metallicity dependent star formation rates

In this model, star formation occurs in gravitationally bound protocluster clumps embedded in larger giant molecular clouds with the protocluster clump mass function following a power-law function with a slope of -2.

Metallicity-dependent feedback is generated by the winds of OB stars (M>~5M_{sun}_) that form in the clumps. The quenching of star formation in clumps of decreasing metallicity occurs at later epochs due to weaker wind luminosities, thus resulting in higher final star formation efficiencies (SFE_exp_). By combining SFE_exp_ with the timescales on which gas expulsion occurs, we derive the metallicity-dependent SFR per unit time in this model as a function of {Sigma}_g_.