Radio Halo Formation through Magnetoturbulent Particle Acceleration in Clusters of Galaxies
Radio Halo Formation through Magnetoturbulent Particle Acceleration in Clusters of Galaxies
复制标题
星系团中磁湍流粒子加速形成射电晕
DOI：
10.1086/342224
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
S. Shibata
中科院分区：
文献类型：
--
作者：
H. Ohno;M. Takizawa;S. Shibata
我们发展了一个宇宙线（CR）电子在星系的射电晕团的磁湍流模型。对于给定的湍流Alfvén波的谱，计算了CR电子的稳态动量分布函数。所得到的CR电子分布产生的无线电频谱进行比较，观察到的后发座射电晕的无线电频谱。我们发现，当湍流阿尔文波的谱指数为~2.8时，后发座星系团的观测射电谱得到了很好的再现。得到的湍流阿尔文波的能谱比湍流理论所预期的要陡，这表明粒子加速的反作用。拟合过程约束湍流Alfvén波的振幅以及谱指数。然后，我们估计的湍流阿尔芬波的耗散，这是发现小于由X射线辐射的冷却速率。我们认为，湍流是足够的粒子加速开发的集群包含无线电晕。最有可能的情况是，星系团的合并产生了湍流，并产生了相对论性电子。
We develop a magnetoturbulent model for the cosmic-ray (CR) electrons seen in the radio halo clusters of galaxies. Steady-state momentum distribution functions of the CR electrons are calculated for given spectra of the turbulent Alfvén waves. The radio spectrum produced by the obtained CR electron distribution is compared to the observed radio spectrum of the Coma radio halo. We find that the observed radio spectrum of the Coma Cluster is well reproduced when the spectral index of the turbulent Alfvén waves is ~2.8. The obtained energy spectrum of the turbulent Alfvén waves is steeper than that expected from the turbulence theory, suggesting back-reaction of the particle acceleration. The fitting procedure constraints the amplitude of the turbulent Alfvén waves as well as the spectral index. Then we estimate the dissipation of the turbulent Alfvén waves, which is found to be less than the cooling rate by X-ray radiation. We suggest that the turbulence that is sufficient for particle acceleration is developed in the clusters containing the radio halo. It is most likely that cluster mergers create the turbulence and seed relativistic electrons.