The primordial clouds in the mini-halos hatch the first generation stars of
the universe, which play a crucial role in cosmic evolution. In this paper, we
investigate how the turbulence impacts the structure of primordial star-forming
cloud. Previous cosmological simulations of the first star formation predicted
a typical mass of around 100Mββ, which conflicts with
recent observations of extremely metal-poor stars suggesting a lower mass scale
of around 25Mββ. The discrepancy may arise from unresolved
turbulence in the star-forming cloud, driven by primordial gas accretion during
mini-halo formation in the previous simulation. To quantitatively examine the
turbulence effect on the primordial cloud formation, we employ the adaptive
mesh refinement code Enzo to model the gas cloud with primordial
composition, including artificial-driven turbulence on the cloud scale and
relevant gas physics. This artificial-driven turbulence utilizes a stochastic
forcing model to mimic the unresolved turbulence inside mini-halos. Our results
show that turbulence with high Mach number and compressional mode effectively
fragments the cloud into several clumps, each with dense cores of 22.7β174.9Mββ that undergo Jeans instability to form stars.
Fragmentation caused by intense and compressive turbulence prevents the runaway
collapse of the cloud. The self-bound clumps with smaller masses in turbulent
primordial cloud suggest a possible pathway to decrease the theoretical mass
scale of first stars, further reconciling the mass discrepancy between
simulations and observations.Comment: All comments are welcome. Submitted to MNRAS. (13 pages, 10 figures,
2 tables