Long-Term Evolution of Supernova Remnants in Magnetized Interstellar Medium
Hanayama, H. and Tomisaka, K.

The evolution of supernova remnants (SNRs) is studied, with particular attention to the effect of magnetic fields with axisymmetric two-dimensional magnetohydrodynamical simulations. The evolution of magnetic SNRs is the same as non-magnetic ones in the adiabatic Sedov stage. After a thin shell is formed, the shell is driven by the pressure of the hot interior gas (bubble). Evolution in the pressure-driven snow-plow phase is much affected by the magnetic field. The shell sweeping the magnetic field lines thickens owing to the magnetic pressure force. After 5 x 105yr - 2 x 106yr, the inner boundary of the thick shell begins to contract. This compresses the hot bubble radially and maintains its thermal pressure. Thus, the bubble forms a prolate spheroidal shape and becomes thinner and thinner, since it expands in a direction parallel to the magnetic field for B0 >~ 3 mu G. Finally, the bubble contracts. The porosity of the hot low-density gas in ISM is reduced, taking the effect of the magnetic field into account.

(submitted to ApJ, July, 2005; accepted Dec. 2005)