Pop. III stars from turbulent fragmentation at redshift ~ 11

Abstract

We report results from a cosmological simulation with non-equilibrium chemistry of 21 species, including H2, HD, and LiH molecular cooling. Starting from cosmological initial conditions, we focus on the evolution of the central 1.8 Kpc region of a 3 x 10^7 Msun halo. The crossing of a few 10^6 Msun halos and the gas accretion through larger scale filaments generate a turbulent environment within this region. Due to the short cooling time caused by the non-equilibrium formation of H2, the supersonic turbulence results in a very fragmented mass distribution, where dense, gravitationally unstable clumps emerge from a complex network of dense filaments. At z=10.87, we find approximately 25 well defined, gravitationally unstable clumps, with masses of 4 x 10^3-9 x 10^5 Msun, temperatures of approximately 300K, and cooling times much shorter than the free-fall time. Only the initial phase of the collapse of individual clumps is spatially resolved in the simulation. Depending on the density reached in the collapse, the estimated average Bonnor-Ebert masses are in the range 200-800 Msun. We speculate that each clump may further fragment into a cluster of stars with a characteristic mass in the neighborhood of 50 Msun. This process at z ~ 11 may represent the dominant mode of Pop. III star formation, causing a rapid chemical enrichment of the protogalactic environment.

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• Star Formation in the First Galaxies I: Collapse Delayed by Lyman-Werner Radiation
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• Detection of isolated population III stars with the James Webb Space Telescope
• The Free-Fall time of finite Sheets and Filaments
• The first galaxies: simulating their feedback-regulated assembly
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• Gas infall into atomic cooling haloes: on the formation of protogalactic disks and supermassive black holes at z > 10
• Dark Matter Halo Environment for Primordial Star Formation
• Feedback from the IR Background in the Early Universe
• Stellar Mass Black Holes in Young Galaxies
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• Dark matter merging induced turbulence as an efficient engine for gas cooling
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• Cosmic Reionization and the First Nonlinear Structures in the Universe
• Saturation level of turbulence in collapsing gas clouds
• Over-cooled haloes at z > 10: a route to form low-mass first stars
• Formation of the First Galaxies: Theory and Simulations