The relation between accretion rates and the initial mass function in hydrodynamical simulations of star formation

Abstract

We analyse a hydrodynamical simulation of star formation. Sink particles in the simulations which represent stars show episodic growth, which is presumably accretion from a core that can be regularly replenished in response to the fluctuating conditions in the local environment. The accretion rates follow $\dot{m}\propto m^{2/3}$, as expected from accretion in a gas-dominated potential, but with substantial variations over-laid on this. The growth times follow an exponential distribution which is tapered at long times due to the finite length of the simulation. The initial collapse masses have an approximately lognormal distribution with already an onset of a power-law at large masses. The sink particle mass function can be reproduced with a non-linear stochastic process, with fluctuating accretion rates $\propto m^{2/3}$, a distribution of seed masses and a distribution of growth times. All three factors contribute equally to the form of the final sink mass function. We find that the upper power law tail of the IMF is unrelated to Bondi-Hoyle accretion.

13 pages, 13 figures, MNRAS accepted

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• Bondi-Hoyle-Littleton accretion and the upper mass stellar IMF
• From the CMF to the IMF: Beyond the Core-Collapse Model
• The Origin of the Stellar Mass Distribution and Multiplicity
• The IMF and multiplicity of stars from gravity, turbulence, magnetic fields, radiation and outflow feedback
• How first hydrostatic cores, tidal forces and gravo-turbulent fluctuations set the characteristic mass of stars
• The role of the turbulence driving mode for the Initial Mass Function
• On the emergent System Mass Function: the contest between accretion and fragmentation
• Binaries traveling through a gaseous medium: Dynamical drag forces and internal torques
• The Role of Gravity in Producing Power-Law Mass Functions
• An alternative model for the origin of gaps in circumstellar disks
• The fragmentation of molecular clouds in starburst environments
• On the coupled origin of the stellar IMF and multiplicity