Magnetic Fields in Primordial Galaxies
  Magnetic fields play a vital role in numerous astrophysical processes such as
star formation and the interstellar medium. In particular, their role in the
formation and evolution of galaxies is not well understood. This paper presents
high-resolution magnetohydrodynamic (MHD) simulations performed with GIZMO to
investigate the effect of magnetic fields on primordial galaxy formation.
Physical processes such as relevant gas physics (e.g., gas cooling and gas
chemistry), star formation, stellar and supernova feedback, and chemical
enrichment were considered in the simulations. The simulation results suggest
that cosmic magnetic fields can be amplified from 1e-13 G to a few microgauss
during cosmic structure evolution and galaxy formation. In the ideal MHD
setting, in primordial galaxies at z>8, the magnetic energy is less than the
thermal and kinetic energy, and therefore, magnetic fields hardly affect the
gas dynamics and star formation in these galaxies. Specifically, the
consideration of micro-physics properties such as metal diffusion, heat
conduction, and viscosity in the MHD simulations, could increase the magnetic
field strength. Notably, metal diffusion reduced gas cooling by decreasing the
metallicity and thereby suppresses star formation in the primordial galaxies.
As a result, the cosmic re-ionization driven by these primordial galaxies may
be delayed.
