Evolutions of Magnetized Supernova Remnants

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1. Evolutions of magnetized supernova remnants are studied with the ideal MHD simulation. Poloidal magnetic fields are taken into account and a two-dimensional axisymmetric MHD code is used.2. (1) "Monotonic Scheme" (a kind of TVD schemes) and "Constrained Transport Scheme, " which conserves strictly the divergence of magnetic fields, are adopted.(2) It is shown that the "Nested Grid" technique is applicable to the MHD simulations.3. The effect of the magnetic fields becomes crucial in a late phase of supernova remnants.(1) In the case of 5*10^<50> ergs of the explosion energy and 0.3cm^<-3> of the ambient density, the magnetic fields with B_0=5muG reduces the volume occupied with a hot gas to -20% of the volume expected for a nonmagnetic supernova remnant.(2) The magnetic tension plays a role after -1 Myr has passed since the supernova explosion occurs. The supernova remnant contracts due to the magnetic tension.4. This indicates that the volume fraction of hot interstellar matter seems much smaller than that suggested previously.