CosmoMHD: A Cosmological Magnetohydrodynamics Code

In this era of precision cosmology, a detailed physical understanding on theevolution of cosmic baryons is required. Cosmic magnetic fields, though stillpoorly understood, may represent an important component in the global cosmicenergy flow that affects the baryon dynamics. We have developed anEulerian-based cosmological magnetohydrodynamics code (CosmoMHD) with modernshock capturing schemes to study the formation and evolution of cosmicstructures in the presence of magnetic fields. The code solves the ideal MHDequations as well as the non-equilibrium rate equations for multiple species,the Vlasov equation for dynamics of collisionless particles, the Poisson'sequation for the gravitational potential field and the equation for theevolution of the intergalactic ionizing radiation field. In addition, adetailed star formation prescription and feedback processes are implemented.Several methods for solving the MHD by high-resolution schemes withfinite-volume and finite-difference methods are implemented. Thedivergence-free condition of the magnetic fields is preserved at a level ofcomputer roundoff error via the constraint transport method. We have alsoimplemented a high-resolution method via dual-equation formulations to trackthe thermal energy accurately in very high Mach number or high Alfven-Machnumber regions. Several numerical tests have demonstrated the efficacy of theproposed schemes.Comment: 10 figures, submitted to ApJ