Magnetically Regulated Gas Accretion in High-Redshift Galactic Disks
  Disk galaxies are in hydrostatic equilibrium along their vertical axis. The
pressure allowing for this configuration consists of thermal, turbulent,
magnetic and cosmic ray components. For the Milky Way(MW) the thermal pressure
contributes ~10% of the total pressure near the plane, with this fraction
dropping towards higher altitudes. Out of the rest, magnetic fields contribute
~1/3 of the pressure to distances of ~3kpc above the disk plane. In this letter
we attempt to extrapolate these local values to high redshift, rapidly
accreting, rapidly star forming disk galaxies and study the effect of the extra
pressure sources on the accretion of gas onto the galaxies. In particular,
magnetic field tension may convert a smooth cold-flow accretion to clumpy,
irregular star formation regions and rates. The infalling gas accumulates on
the edge of the magnetic fields, supported by magnetic tension. When the mass
of the infalling gas exceeds some threshold mass, its gravitational force
cannot be balanced by magnetic tension anymore, and it falls toward the disk's
plane, rapidly making stars. Simplified estimations of this threshold mass are
consistent with clumpy star formation observed in SINS, UDF, GOODS and GEMS
surveys. We discuss the shortcomings of pure hydrodynamic codes in simulating
the accretion of cold flows into galaxies, and emphasize the need for
magneto-hydrodynamic simulations
