Magnetic dissipation in the Crab nebula
Magnetic dissipation in the Crab nebula
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DOI：
10.1093/mnras/sts214
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发表时间：
2012-07
影响因子：
4.8
通讯作者：
S. Komissarov
中科院分区：
文献类型：
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作者：
S. Komissarov
磁耗散经常被用来作为伽马射线暴和活动星系核中观测到的相对论流发射的一种方式。脉冲风星云提供了更接近家庭的宇宙实验室，可以用来测试假设。为此，我们重新分析了蟹状星云脉冲星的自旋功率、蟹状星云的能量和磁场的观测数据。我们表明，除非蟹状星云脉冲星的磁倾角非常接近90度，否则条纹风的整体磁化强度在其条纹完全耗散后显着高于Kennel-Coroniti模型和最近的PulsarWind星云轴对称模拟中推导出的磁化强度。另一方面，较高的风磁化强度与蟹状星云观测到的低磁场相冲突，除非它在星云内部也受到有效的耗散。对于可能的45度倾角，数据需要大约80年的时间尺度上的磁耗散，这与星云的寿命相比很短，但与蟹状星云的伽马射线耀斑的时间尺度相比很长。
Magnetic dissipation is frequently invoked as a way of powering the observed emission of relativistic flows in Gamma-ray bursts and active galactic nuclei. PulsarWind Nebulae provide closer to home cosmic laboratories which can be used to test the hypothesis. To this end, we reanalyze the observational data on the spindown power of the Crab pulsar, energetics of the Crab nebula and its magnetic field. We show that unless the magnetic inclination angle of the Crab pulsar is very close to 90 degrees the overall magnetization of the striped wind after total dissipation of its stripes is significantly higher than that deduced in the Kennel-Coroniti model and recent axisymmetric simulations of PulsarWind Nebulae. On the other hand, higher wind magnetization is in conflict with the observed low magnetic field of the Crab nebula, unless it is subject to efficient dissipation inside the nebula as well. For the likely inclination angle of 45 degrees the data require magnetic dissipation on the time-scale of about 80 years, which is short compared to the lifetime of the nebula but long compared to the time-scale of Crab's gamma-ray flares.