Extremely fast acceleration of cosmic rays in a supernova remnant
Extremely fast acceleration of cosmic rays in a supernova remnant
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DOI：
10.1038/nature06210
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发表时间：
2007-10
期刊：
影响因子：
64.8
通讯作者：
Y. Uchiyama;F. Aharonian;Takaaki Tanaka;Tadayuki Takahashi;Y. Maeda
中科院分区：
文献类型：
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作者：
Y. Uchiyama;F. Aharonian;Takaaki Tanaka;Tadayuki Takahashi;Y. Maeda
银河宇宙射线（CR）被广泛认为是由超新星喷出物膨胀到星际介质中的冲击波加速的。这个长期存在的猜想中的一个关键问题是理论预测，星际磁场可以通过宇宙射线产生的磁流体动力学波在年轻超新星遗迹（SNR）的冲击下大幅放大。在这里，我们报告了SNR RX J1713.7-3946外壳中X射线热点在一年时间尺度上的增亮和衰减。这种快速的变化表明，X射线是由超相对论电子通过同步加速器过程产生的，电子加速确实发生在强磁化环境中，表明磁场放大了100倍以上。X射线的可变性也意味着我们已经目睹了电子在真实的时间中持续的冲击加速。独立地，RX J1713.7-3946的宽带X射线光谱测量表明，电子加速在最有效的（'玻姆扩散'）制度中进行。综合起来，这两个结果为年轻超新星遗迹中质子和原子核加速到1 PeV（1015 eV）或更高的能量提供了有力的论据。
Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) through magnetohydrodynamic waves generated by cosmic rays,. Here we report a discovery of the brightening and decay of X-ray hot spots in the shell of the SNR RX J1713.7-3946 on a one-year timescale. This rapid variability shows that the X-rays are produced by ultrarelativistic electrons through a synchrotron process and that electron acceleration does indeed take place in a strongly magnetized environment, indicating amplification of the magnetic field by a factor of more than 100. The X-ray variability also implies that we have witnessed the ongoing shock-acceleration of electrons in real time. Independently, broadband X-ray spectrometric measurements of RX J1713.7-3946 indicate that electron acceleration proceeds in the most effective (‘Bohm-diffusion’) regime. Taken together, these two results provide a strong argument for acceleration of protons and nuclei to energies of 1 PeV (1015eV) and beyond in young supernova remnants.