Hu Yue, Stuardi C, Lazarian A, Brunetti G, Bonafede A, Ho Ka Wai
Department of Physics, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Department of Astronomy, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Nat Commun. 2024 Feb 6;15(1):1006. doi: 10.1038/s41467-024-45164-8.
Magnetic fields and their dynamical interplay with matter in galaxy clusters contribute to the physical properties and evolution of the intracluster medium. However, the current understanding of the origin and properties of cluster magnetic fields is still limited by observational challenges. In this article, we map the magnetic fields at hundreds-kpc scales of five clusters RXC J1314.4-2515, Abell 2345, Abell 3376, MCXC J0352.4-7401, and El Gordo using the synchrotron intensity gradient technique in conjunction with high-resolution radio observations from the Jansky Very Large Array (JVLA) and the Karoo Array Telescope (MeerKAT). We demonstrate that the magnetic field orientation of radio relics derived from synchrotron intensity gradient is in agreement with that obtained with synchrotron polarization. Most importantly, the synchrotron intensity gradient is not limited by Faraday depolarization in the cluster central regions and allows us to map magnetic fields in the radio halos of RXC J1314.4-2515 and El Gordo. We find that magnetic fields in radio halos exhibit a preferential direction along the major merger axis and show turbulent structures at higher angular resolution. The results are consistent with expectations from numerical simulations, which predict turbulent magnetic fields in cluster mergers that are stirred and amplified by matter motions.
磁场及其在星系团中与物质的动态相互作用，对星系团内介质的物理性质和演化有重要影响。然而，目前对星系团磁场的起源和性质的理解仍受观测挑战的限制。在本文中，我们利用同步辐射强度梯度技术，结合来自 Jansky 甚大阵列（JVLA）和卡鲁阵列望远镜（MeerKAT）的高分辨率射电观测，绘制了五个星系团 RXC J1314.4 - 2515、阿贝尔 2345、阿贝尔 3376、MCXC J0352.4 - 7401 和埃尔戈多在数百千秒差距尺度上的磁场图。我们证明，通过同步辐射强度梯度得出的射电遗迹磁场方向与通过同步辐射偏振获得的方向一致。最重要的是，同步辐射强度梯度不受星系团中心区域法拉第去极化的限制，使我们能够绘制 RXC J1314.4 - 2515 和埃尔戈多射电晕中的磁场图。我们发现，射电晕中的磁场沿主要合并轴呈现出优先方向，并在更高角分辨率下显示出湍流结构。这些结果与数值模拟的预期一致，数值模拟预测星系团合并中会产生由物质运动搅动和放大的湍流磁场。
