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Forming the First Stars in the Universe: The Fragmentation of Primordial Gas

Volker Bromm·Paolo S. Coppi·Richard B. Larson
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Abstract

In order to constrain the initial mass function (IMF) of the first generation of stars (Population III), we investigate the fragmentation properties of metal-free gas in the context of a hierarchical model of structure formation. We investigate the evolution of an isolated 3-sigma peak of mass 2x10^6 M_solar which collapses at z_coll=30 using Smoothed Particle Hydrodynamics. We find that the gas dissipatively settles into a rotationally supported disk which has a very filamentary morphology. The gas in these filaments is Jeans unstable with M_J~10^3 M_solar. Fragmentation leads to the formation of high density (n>10^8 cm^-3) clumps which subsequently grow in mass by accreting surrounding gas and by merging with other clumps up to masses of ~10^4 M_solar. This suggests that the very first stars were rather massive. We explore the complex dynamics of the merging and tidal disruption of these clumps by following their evolution over a few dynamical times.

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Volker Bromm, Paolo S. Coppi, Richard B. Larson. 1999-10-13. Forming the First Stars in the Universe: The Fragmentation of Primordial Gas. https://doi.org/10.1086/312385

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