Two-dimensional magnetohydrodynamics simulations of young Type Ia supernova remnants
Two-dimensional magnetohydrodynamics simulations of young Type Ia supernova remnants
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DOI：
10.1111/j.1365-2966.2012.21405.x
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发表时间：
2012-08
影响因子：
4.8
通讯作者：
J. Fang;Li Zhang
中科院分区：
文献类型：
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作者：
J. Fang;Li Zhang
利用二维磁流体动力学 (MHD) 模拟，我们研究了 Ia 型超新星遗迹 (SNR) 在均匀环境介质中或与致密团块相互作用中演化的动力学特性。初始条件假设超新星喷射物的膨胀具有自由惯性，喷射物外部呈幂律密度分布。为了考虑扩散激波加速过程和加速粒子从激波前沿逃逸的影响，我们在模拟中使用不同的绝热指数来研究 Ia 型信噪比的动态演化。此外，我们还研究了 SNR 与小团块或大团块的相互作用。当喷射物在环境介质中超音速流动时，产生具有接触不连续性的双激波结构；瑞利泰勒不稳定性清楚地显示为密度等值线图中接触不连续点附近的手指，并且由于瑞利泰勒手指周围的不稳定性可以触发高密度和高磁场。我们用不同的绝热指数进行模拟，结果表明，绝热指数越小，产生的间激波区域越窄，因为信噪比激波的压缩比更大。绝热指数越小，瑞利泰勒不稳定性对正向和反向激波形态的影响越显着。最后，SNR与致密团块相互作用的模拟表明，碰撞后残余物的形态发生了很大的扭曲，并且当SNR与大致密团块碰撞时可以产生高密度和高磁场的细丝。
Using two-dimensional magnetohydrodynamics (MHD) simulations, we investigate the dynamical properties of Type Ia supernova remnants (SNRs) evolved either in a uniform ambient medium or from an interaction with a dense clump. The initial conditions assume that the expansion of the supernova ejecta is of free inertia with a power-law density distribution in the outer part of the ejecta. To include the effects of the diffusive shock acceleration process and the escape of the accelerated particles from the shock front, we use different adiabatic indices in the simulations to study the dynamical evolution of the Type Ia SNRs. Moreover, we investigate the interactions of a SNR with either a small or a large clump. A double-shock structure with a contact discontinuity is produced as the ejecta flow supersonically in the ambient medium; RayleighTaylor instability is clearly shown as fingers near the contact discontinuity in the contour maps of density, and a high density and a high magnetic field can be triggered because of the instability around the RayleighTaylor fingers. We perform simulations with different adiabatic indices, and the results show that a narrower intershock region is produced with a smaller adiabatic index because a larger compression ratio for the SNR shock is induced. The influence of the RayleighTaylor instability on the morphologies of both the forward and reverse shocks is more significant with a smaller adiabatic index. Finally, the simulations of a SNR interacting with a dense clump show that the morphology of the remnant is greatly twisted after the collision, and a filament with a high density and a high magnetic field can be produced as a SNR colliding with a large dense clump.