SHOCK HEATING OF THE MERGING GALAXY CLUSTER A521
SHOCK HEATING OF THE MERGING GALAXY CLUSTER A521
复制标题
合并星系团 A521 的剧烈加热
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
G. Brunetti
中科院分区：
文献类型：
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作者：
H. Bourdin;P. Mazzotta;M. Markevitch;M. Markevitch;S. Giacintucci;G. Brunetti
A521 是一个相互作用的星系团，位于 z = 0.247，拥有一个与东部射电遗迹相连的低频射电晕。钱德拉之前的观测暗示在遗迹位置存在X射线亮度边缘，这可能是激波锋。我们分析了最近使用 XMM-Newton 对 A521 进行的深度观测，以探测星团结构直至无线电发射覆盖的最外层区域。星团大气表现出各种亮度和温度各向异性。特别是，两个簇核心似乎被两个冷锋分开。我们发现了两个激波锋，一个是钱德拉提出的，正在向东传播，另一个则向西南星团外围传播。两个主要相互作用的星团似乎被一个激波加热区域分开，该区域表现出与射电晕的空间相关性。无线电遗迹的外边缘在空间上与激波锋面重合，表明这种冲击是遗迹中宇宙射线电子产生的原因。在费米 I 加速机制的假设下，由气体密度跃变得出的激波前沿的传播方向和马赫数 M = 2.4 ± 0.2 与射电频谱指数的预期一致。
A521 is an interacting galaxy cluster located at z = 0.247, hosting a low-frequency radio halo connected to an eastern radio relic. Previous Chandra observations hinted at the presence of an X-ray brightness edge at the position of the relic, which may be a shock front. We analyze a deep observation of A521 recently performed with XMM-Newton in order to probe the cluster structure up to the outermost regions covered by the radio emission. The cluster atmosphere exhibits various brightness and temperature anisotropies. In particular, two cluster cores appear to be separated by two cold fronts. We find two shock fronts, one that was suggested by Chandra and that is propagating to the east, and another to the southwestern cluster outskirt. The two main interacting clusters appear to be separated by a shock-heated region, which exhibits a spatial correlation with the radio halo. The outer edge of the radio relic coincides spatially with a shock front, suggesting that this shock is responsible for the generation of cosmic-ray electrons in the relic. The propagation direction and Mach number of the shock front derived from the gas density jump, M = 2.4 ± 0.2, are consistent with expectations from the radio spectral index, under the assumption of Fermi I acceleration mechanism.