A Bayesian view on Faraday rotation maps - Seeing the magnetic power spectra in galaxy clusters
A Bayesian view on Faraday rotation maps - Seeing the magnetic power spectra in galaxy clusters
复制标题
法拉第旋转图的贝叶斯视图 - 查看星系团中的磁功率谱
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
T. Ensslin
中科院分区：
文献类型：
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作者：
C. Vogt;T. Ensslin
我们提出了扩展无线电源的法拉第旋转测量（RM）图的贝叶斯最大似然分析，以确定星系团中的磁场功率谱。使用这种方法，可以确定测量中的不确定性。我们将这种方法应用于 Hydra A 的 RM 图并推导出簇磁场的功率谱。对于 Hydra A，我们测量了至少一个数量级的 -5/3 的光谱指数，这意味着柯尔莫哥洛夫型湍流。我们发现磁功率集中在一个主导尺度 ∼3 kpc 上，因为磁自相关长度为 λB = 3 ± 0.5 kpc。此外，我们研究了采样体积假设（由窗函数描述）对磁功率谱的影响。对于最可能的几何形状，中心磁场强度被确定为 ∼7 ± 2 µG。
We present a Bayesian maximum likelihood analysis of Faraday rotation measure (RM) maps of extended radio sources to determine magnetic field power spectra in clusters of galaxies. Using this approach, it is possible to determine the uncertainties in the measurements. We apply this approach to the RM map of Hydra A and derive the power spectrum of the cluster magnetic field. For Hydra A, we measure a spectral index of −5/3 over at least one order of magnitude implying Kolmogorov type turbulence. We find a dominant scale ∼3 kpc on which the magnetic power is concentrated, since the magnetic autocorrelation length is λB = 3 ± 0.5 kpc. Furthermore, we investigate the influences of the assumption about the sampling volume (described by a window function) on the magnetic power spectrum. The central magnetic field strength was determined to be ∼7 ± 2 µG for the most likely geometries.