Amplification of turbulence in contracting prestellar cores in primordial minihalos

Abstract

We investigate the amplification of turbulence through gravitational contraction of the primordial gas in minihalos. We perform numerical simulations to follow the cloud collapse, assuming polytropic equations of state for different initial turbulent Mach numbers and resolutions. We find that the turbulent velocity is amplified solely by gravitational contraction, and eventually becomes comparable to the sound speed, even for small initial turbulent Mach numbers (${\mathcal{M}}_0\gtrsim 0.05$). We derive an analytic formula for the amplification of turbulent velocity in a collapsing cloud, and find that our numerical results are consistent with the formula. These results suggest that the turbulence can play an important role in collapsing clouds for general cases.

17 pages, 16 figures, 2 tables, accepted for publication in ApJ

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• Supermassive Star Formation in Magnetized Atomic-Cooling Gas Clouds: Enhanced Accretion, Intermittent Fragmentation, and Continuous Mergers
• Impact of turbulence intensity and fragmentation velocity on dust particle size evolution and non-ideal magnetohydrodynamics effects
• Amplification and saturation of turbulent magnetic field in collapsing primordial gas clouds
• Metallicity Dependence of Molecular Cloud Hierarchical Structure at Early Evolutionary Stages
• Saturation level of turbulence in collapsing gas clouds
• Amplification and generation of turbulence during self-gravitating collapse