Metallicity and the Universality of the IMF

Abstract

The stellar initial mass function (IMF), along with the star formation rate, is one of the fundamental properties that any theory of star formation must explain. An interesting feature of the IMF is that it appears to be remarkably universal across a wide range of environments. Particularly, there appears to be little variation in either the characteristic mass of the IMF or its high-mass tail between clusters with different metallicities. Previous attempts to understand this apparent independence of metallicity have not accounted for radiation feedback from high-mass protostars, which can dominate the energy balance of the gas in star-forming regions. We extend this work, showing that the fragmentation of molecular gas should depend only weakly on the amount of dust present, even when the primary heating source is radiation from massive protostars. First, we report a series of core collapse simulations using the ORION AMR code that systematically vary the dust opacity and show explicitly that this has little effect on the temperature or fragmentation of the gas. Then, we provide an analytic argument for why the IMF varies so little in observed star clusters, even as the metallicity varies by a factor of 100.

11 pages, 6 figures, emulateapj format, accepted to ApJ. Typos removed, references added, and discussion revised in section 3.2. Conclusions unchanged

References in corpus (15)

• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• Star formation through gravitational collapse and competitive accretion
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Importance of Radiative Feedback for the Stellar Initial Mass Function
• Limiting Accretion onto Massive Stars by Fragmentation-Induced Starvation
• Equations and Algorithms for Mixed Frame Flux-Limited Diffusion Radiation Hydrodynamics
• On the Constancy of the Characteristic Mass of Young Stars
• Interferometric multi-wavelength (sub)millimeter continuum study of the young high-mass protocluster IRAS05358+3543
• The Fate of Discs around Massive Stars in Young Clusters
• Star Formation in the Extreme Outer Galaxy: Digel Cloud 2 Clusters
• A multigroup diffusion solver using pseudo transient continuation for a radiation-hydrodynamic code with patch-based AMR
• Far-Infrared Spectral Energy Distributions and Photometric Redshifts of Dusty Galaxies