EPoS Contribution

Can we have both competitive accretion AND fragmentation? Paul C. Clark Cardiff U, Cardiff, UK
The “competitive accretion” model of the initial mass function (IMF) appears to play an important role in essentially all the numerical simulations conducted to date, but is difficult to reconcile with the observations of prestellar cores, and their similarity in their mass distribution to the IMF of stars. However, we highlight in this talk that competitive accretion requires that the accretion onto existing protostars be balanced by the formation of new stars — a phenomenon not discussed in the original model. As such, we present a model in which the formation of the IMF is actually the balance accretion and fragmentation; the classic Salpeter slope arises from this balance, provided certain conditions are met. Further, this model allows both competitive accretion and core-mass/fragmentation theory to coexist, provided they occur at slightly different times in the cloud’s evolution. In addition, we discuss how the conditions in the galactic centre, where the gas heating is dominated by cosmic rays (as opposed to photoelectric heating, which dominates in the solar neighbourhood), may lead to a top-heavy protostellar IMF. This effect arises due to the increase in the accretion rate from the hotter gas in the galactic centre, coupled with the lack of fragmentation due to the longer cooling times.
Collaborators: A. P. Whitworth M. Cusack	Key publication Relevant topic(s): Core MF Fragmentation Initial MF
Relevant Big Question: The origin of the initial mass function of stars