Back to Volume
Paper: Competitive Accretion in Sheet Geometry and the Stellar IMF
Volume: 440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function?
Page: 107
Authors: Hsu, W.; Hartmann, L.; Heitsch, F.; Gómez, G. C.
Abstract: We report a set of numerical experiments addressing the applicability of competitive accretion to explain the high-mass end of the stellar initial mass function in a sheet geometry with shallow gravitational potential, in contrast to most previous simulations which have assumed formation in a cluster gravitational potential. Our flat cloud geometry is motivated by models of molecular cloud formation due to large-scale flows in the interstellar medium. The experiments consisted of smoothed particle hydrodynamics simulations of gas accretion onto sink particles formed rapidly from Jeans-unstable dense clumps placed randomly in the finite sheet. We considered both clumps of equal mass and gaussian distributions of masses, and either uniform or spatially-varying gas densities. The sink mass function develops a power law tail at high masses, with dN/dlogM ∝ M–Γ. The accretion rates of individual sinks follow M ∝ M2 at high masses; this results in a continual flattening of the slope of the mass function towards an asymptotic form Γ1 (where the Salpeter slope is Γ = 1.35). The asymptotic limit is most rapidly reached when starting from a relatively broad distribution of initial sink masses. Although these simulations are highly idealized, the results suggest that competitive accretion may be relevant in a wider variety of environments than previously considered.
Back to Volume