The Growth of Baryonic Structure in the Presence of Cosmological   Magnetic Pressure
  We follow the growth of baryonic structure in the presence of a magnetic field within an approximate cosmological magneto-hydrodynamic simulation, produced by adding an (isotropic) magnetic pressure related to the local gas pressure. We perform an ensemble of these simulations to follow the amplification of the field with time. By using a variety of initial field strengths and changing the slope of the power law that governs the way the field grows with increasing density we span the range of current observations and demonstrate the size of the effect realistic magnetic fields could have on the central density of groups and clusters. A strong magnetic field significantly reduces the central gas density which, in turn, reduces observable quantities such as the X-ray luminosity. 
L. Gazzola, E. J. King, F. R. Pearce and P. Coles