The Stellar IMF in Low-Metallicity Gas

摘要

The observed slope at the high-mass end of the initial mass function displays a remark-able universality in a wide variety of physical environments. We argue that competitive accretion – the ongoing accretion of gas from a common reservoir by a collection of protostellar cores –provides a natural explanation for this universal slope. We show that the conditions required for competitive accretion to operate can he achieved even in gas with a metallicity as low as 10~(-5)Z., and hence argue that even the lowest metallicity star-forming systems should produce stars with an IMF that is similar to that for present-day stars.