Synchrotron nebulae created by anisotropic magnetized pulsar winds
Synchrotron nebulae created by anisotropic magnetized pulsar winds
复制标题
由各向异性磁化脉冲星风产生的同步加速器星云
DOI：
10.1111/j.1365-2966.2004.07597.x
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发表时间：
2004
影响因子：
4.8
通讯作者：
Y. Lyubarsky
中科院分区：
文献类型：
--
作者：
S. Komissarov;Y. Lyubarsky
在本文中，我们给出了一个详细的描述，第一次尝试研究的性质，由一个磁化脉冲星风产生的流在一个plerionic星云通过完全相对论磁流体动力学（MHD）模拟。根据目前脉冲星风的理论模型，我们假设在赤道方向上风的磁化强度下降到零，但其能量通量达到最大值。我们的2D轴对称模拟的结果显示复杂的动力学的后冲击流，非常不同的稳定的准径向流出假设在早期的分析模型plerions。终端激波的形状是扭曲的环面，大部分下游气流最初被限制在赤道面内。如果风的磁化强度高于一定值，磁环向应力会阻止赤道盘表层的外流，并将其重定向为磁约束极喷流。赤道盘内层的外流继续，直到它到达缓慢膨胀的外壳，然后转回来，形成充满中纬度星云体积的涡流。考虑到相对论性光束效应和粒子能量损失，我们模拟了该星云的同步辐射图像。这些图像与钱德拉和哈勃太空望远镜获得的蟹状星云和其他脉冲星风星云的著名图像惊人地相似。它们既有一个环系统，给人一种赤道盘状甚至环形结构的印象，也有准直良好的极地喷流，似乎来自脉冲星。蟹状星云内部的许多细节都可以找到自然的解释，包括赫斯特等人在1995年发现的非常靠近蟹状星云脉冲星的明亮结。
In this paper, we give a detailed description of the first attempt to study the properties of the flow produced by a magnetized pulsar wind within a plerionic nebula via fully relativistic magnetohydrodynamic (MHD) simulations. Following the current theoretical models of pulsar winds, we assume that in the equatorial direction the magnetization of the wind drops to zero but its energy flux reaches a maximum. The results of our 2D axisymmetric simulations reveal complex dynamics of the post-shock flow, very different from the steady quasi-radial outflow assumed in earlier analytical models for plerions. The termination shock has the shape of a distorted torus and most of the downstream flow is initially confined to the equatorial plane. Provided the wind magnetization is higher than a certain value, the magnetic hoop stress stops the outflow in the surface layers of the equatorial disc and redirects it into magnetically confined polar jets. The outflow in the inner layers of the equatorial disc continues until it reaches the slowly expanding outer shell and then turns back and forms the vortex flow filling the nebular volume at intermediate latitudes. We simulated the synchrotron images of the nebula taking into account the relativistic beaming effect and the particle energy losses. These images are strikingly similar to the well-known images of the Crab and other pulsar wind nebulae obtained by Chandra and the Hubble Space Telescope. They exhibit both a system of rings, which makes an impression of an equatorial disc-like or even a toroidal structure, and well-collimated polar jets, which appear to originate from the pulsar. A number of fine details of the inner Crab nebula find natural explanation including the bright knot discovered by Hester et al. in 1995 very close to the Crab pulsar.