RADIO AND X-RAY SHOCKS IN CLUSTERS OF GALAXIES
RADIO AND X-RAY SHOCKS IN CLUSTERS OF GALAXIES
复制标题
星系团中的射电和 X 射线冲击
DOI：
10.1088/0004-637x/812/1/49
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
D. Ryu
中科院分区：
文献类型：
--
作者：
S. E. Hong;Hyesung Kang;D. Ryu
在星系团外围检测到的无线电遗迹被认为是追踪在宇宙冲击中加速的射电发射相对论电子。在这项研究中，我们利用大规模结构形成的宇宙流体动力学模拟数据，并采用扩散激波加速（DSA）模型来产生宇宙射线（CR）电子，构建了投影在天空平面上的模拟星系团的模拟无线电和X射线图。从合成图中提取冲击波和射电遗迹的各种特性，包括冲击马赫数、射电光谱指数和光度，并与观测结果进行比较。这些地图中识别的无线电和 X 射线冲击的很大一部分涉及沿视线 (LOS) 的多个冲击表面，并且地图中冲击分布的形态取决于投影方向。在给定视距内的多个激波中，射电观测倾向于拾取射电频谱较平坦的较强激波，而X射线观测则优先选择动能通量较大的较弱激波。因此，在某些情况下，从无线电和 X 射线观测中得出的激波马赫数和位置可能会彼此不同。我们还发现，合成射电遗迹的频谱指数和射电功率分布与观测到的真实遗迹有些不一致；在靠近星团核心且光谱指数更陡的地方观察到了更多的射电遗迹。我们认为，与此处采用的 DSA 模型相比，如果 Ms ≲ 2 的非常弱的冲击能够更有效地加速 CR 电子，则可以解释这种不一致。
Radio relics detected in the outskirts of galaxy clusters are thought to trace radio-emitting relativistic electrons accelerated at cosmological shocks. In this study, using the cosmological hydrodynamic simulation data for the large-scale structure formation and adopting a diffusive shock acceleration (DSA) model for the production of cosmic-ray (CR) electrons, we construct mock radio and X-ray maps of simulated galaxy clusters that are projected in the sky plane. Various properties of shocks and radio relics, including the shock Mach number, radio spectral index, and luminosity, are extracted from the synthetic maps and compared with observations. A substantial fraction of radio and X-ray shocks identified in these maps involve multiple shock surfaces along lines of sight (LOSs), and the morphology of shock distributions in the maps depends on the projection direction. Among multiple shocks in a given LOS, radio observations tend to pick up stronger shocks with flatter radio spectra, while X-ray observations preferentially select weaker shocks with larger kinetic energy flux. As a result, in some cases the shock Mach numbers and locations derived from radio and X-ray observations could differ from each other. We also find that the distributions of the spectral index and radio power of the synthetic radio relics are somewhat inconsistent with those of observed real relics; a bit more radio relics have been observed closer to the cluster core and with steeper spectral indices. We suggest that the inconsistency could be explained if very weak shocks with Ms ≲ 2 accelerate CR electrons more efficiently, compared with the DSA model adopted here.
影响因子：
4.8
作者：
F. Gasperin;R. V. Weeren;M. Brüggen;F. Vazza;A. Bonafede;H. Intema
通讯作者：
F. Gasperin;R. V. Weeren;M. Brüggen;F. Vazza;A. Bonafede;H. Intema