Magnetic fields in the formation of the first stars.--II Results

Abstract

Beginning with cosmological initial conditions at z=100, we simulate the effects of magnetic fields on the formation of Population III stars and compare our results with the predictions of Paper I. We use Gadget-2 to follow the evolution of the system while the field is weak. We introduce a new method for treating kinematic fields by tracking the evolution of the deformation tensor. The growth rate in this stage of the simulation is lower than expected for diffuse astrophysical plasmas, which have a very low resistivity (high magnetic Prandtl number); we attribute this to the large numerical resistivity in simulations, corresponding to a magnetic Prandtl number of order unity. When the magnetic field begins to be dynamically significant in the core of the minihalo at z=27, we map it onto a uniform grid and follow the evolution in an adaptive mesh refinement, MHD simulation in Orion2. The nonlinear evolution of the field in the Orion2 simulation violates flux-freezing and is consistent with the theory proposed by Xu & Lazarian. The fields approach equipartition with kinetic energy at densities ~ 10^10 - 10^12 cm^-3. When the same calculation is carried out in Orion2 with no magnetic fields, several protostars form, ranging in mass from ~ 1 to 30 M_sol with magnetic fields, only a single ~ 30 M_sol protostar forms by the end of the simulation. Magnetic fields thus suppress the formation of low-mass Pop III stars, yielding a top-heavy Pop III IMF and contributing to the absence of observed Pop III stars.

31 pages, 30 figures, accepted to MNRAS

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Cited by in corpus (20)

• Turbulent Magnetic Field Amplification by the Interaction of Shock Wave and Inhomogeneous Medium
• Timing the r-Process Enrichment of the Ultra-Faint Dwarf Galaxy Reticulum II
• Fundamental scales in the kinematic phase of the turbulent dynamo
• Formation of Massive and Wide First-star Binaries in Radiation Hydrodynamics Simulations
• Exponentially amplified magnetic field eliminates disk fragmentation around the Population III protostar
• From dark matter halos to pre-stellar cores: High resolution follow-up of cosmological Lyman-Werner simulations
• Impact of magnetic fields on Population III star formation
• Gravitational waves from mergers of Population III binary black holes: roles played by two evolution channels
• Non-ideal magnetohydrodynamic simulations of the first star formation: the effect of ambipolar diffusion
• The THESAN-ZOOM project: Population III star formation continues until the end of reionization
• A kiloparsec-scale ordered magnetic field in a galaxy at z=5.6
• Amplification and saturation of turbulent magnetic field in collapsing primordial gas clouds
• The formation of globular clusters with top-heavy initial mass functions
• Population III star formation in the presence of turbulence, magnetic fields and ionizing radiation feedback
• Effects of chemically homogeneous evolution of the first stars on the 21-cm signal and reionization
• Halo Mergers Enhance the Growth of Massive Black Hole Seeds
• Simulating the collapse of rotating primordial gas clouds to study the survival possibility of Pop III protostars
• Radiation magnetohydrodynamics simulations of Population III star formation during the Epoch of Reionization
• The Baryon Budget of Galaxies across the First Billion Years
• Transferring Data from a Voronoi Mesh to an Adaptive Cartesian Grid in Pursuit of Self-consistent Top-down Star Formation