Rotation measures of radio sources in hot galaxy clusters
Rotation measures of radio sources in hot galaxy clusters
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DOI：
10.1051/0004-6361/200913665
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发表时间：
2010-07
影响因子：
6.5
通讯作者：
F. Govoni;K. Dolag;M. Murgia;L. Feretti;S. Schindler;G. Giovannini;W. Boschin;V. Vacca;A. Bonafede
中科院分区：
文献类型：
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作者：
F. Govoni;K. Dolag;M. Murgia;L. Feretti;S. Schindler;G. Giovannini;W. Boschin;V. Vacca;A. Bonafede
目标。这项工作的目标是研究热星系团中射电星系的法拉第旋转测量（RM），以便在磁场强度和星系团内介质的气体温度之间建立可能的联系。方法。我们对位于A401和蛇夫座的两个射电星系、位于A2142的射电星系和位于A2065背景的射电星系的3.6厘米和6厘米处进行了甚大阵列观测。所有这些星系团的特点都是高温。结果。我们以 3 �� 的角分辨率获得了大多数观测到的射电星系的详细 RM 图像。 RM 图像是不完整的，并揭示了大小为几个 kpc 的精细子结构。假设射电星系本身对测量的 RM 没有影响，这些结构表明簇内磁场波动到如此小的尺度。这些新数据与文献中有关较冷星系团的 RM 信息进行了比较。对于距团簇中心的固定投影距离，温度较高的团簇显示出较高的 RM 分布离散度 (σRM)，这主要是因为这些团簇中的气体密度较高。尽管先前已知的射电星系位置处的星团 X 射线表面亮度 (S X) 与 σRM 之间的关系已得到证实，但 σRM – S X 关系与星团温度之间的可能联系（如果存在）非常微弱。因此，就目前的数据而言，不可能在簇内介质的磁场强度和气体温度之间建立严格的联系。
Aims. The goal of this work is to investigate the Faraday rotation measure (RM) of radio galaxies in hot galaxy clusters in order to establish a possible connection between the magnetic field strength and the gas temperature of the intracluster medium. Methods. We performed Very Large Array observations at 3.6 cm and 6 cm of two radio galaxies located in A401 and Ophiuchus, a radio galaxy in A2142, and a radio galaxy located in the background of A2065. All these galaxy clusters are characterized by high temperatures. Results. We obtained detailed RM images at an angular resolution of 3 �� for most of the observed radio galaxies. The RM images are patchy and reveal fine substructures of a few kpc in size. Under the assumption that the radio galaxies themselves have no effect on the measured RMs, these structures indicate that the intracluster magnetic fields fluctuate down to such small scales. These new data are compared with RM information present in the literature for cooler galaxy clusters. For a fixed projected distance from the cluster center, clusters with higher temperature show a higher dispersion of the RM distributions (σRM), mostly because of the higher gas density in these clusters. Although the previously known relation between the clusters X-ray surface brightness (S X) at the radio galaxy location and σRM is confirmed, a possible connection between the σRM − S X relation and the cluster temperature, if present, is very weak. Therefore, in view of the current data, it is impossible to establish a strict link between the magnetic field strength and the gas temperature of the intracluster medium.