Abstract

Contributed Talk - Splinter StarFormation   (MW-1250)

Turbulence in Primordial Dark Matter Halos and Its Impact on the First Star Formation

Chen, Ke-Jung; Ho, Meng-Yuan; Tung, Pei-Cheng
ASIAA/HITS

We present a suite of high-resolution simulations of the first star-forming clouds in 15 minihalos with masses ranging from approximately 10^5 to 10^7 solar masses at redshifts z ≈ 17–20, performed using the GIZMO code. Our simulations include detailed primordial chemistry and cooling and are initialized from the state-of-the-art IllustrisTNG cosmological simulations. To achieve the resolution required to follow primordial star formation, we employ a particle-splitting technique that increases the original resolution by a factor of approximately 100,000, reaching gas and dark matter particle masses of 0.2 and 80 solar masses, respectively. This allows us to resolve gas accretion during the early assembly of minihalos and capture the development of turbulent flows within their central regions. We find that turbulence driven by gas infall into dark matter potential wells is predominantly supersonic, with characteristic Mach numbers ranging from 1.8 to 4.2 and increasing with halo mass. These turbulent motions efficiently stir the gas and promote fragmentation of the central cloud into multiple dense clumps. Several of these clumps have masses between 2.6 and 66.5 solar masses, exceeding their local Jeans masses and undergoing gravitational collapse to form the first stars. Our results suggest that supersonic turbulence is a common feature of primordial minihalos and a key regulator of cloud fragmentation. This turbulence-driven fragmentation naturally produces clumpy star-forming environments and may play an important role in shaping the initial mass function of the first generation of stars.