A2256的Chandra和XMM-牛顿观测：冷锋、合并激波和对IC发射的约束
Chandra and XMM-Newton observations of A2256: cold fronts, merger shocks, and constraint on the IC emission
摘要：
我们提出了深钱德拉和XMM-牛顿观测的一个复杂的合并星系团阿贝尔2256（A2256），主机一个壮观的无线电遗迹（RR）的结果。温度图和金属丰度图显示了西部子星系团（SC）和主星系团（PC）合并的明确证据。我们检测到五个X射线表面亮度边缘。其中三个是冷锋（CFs）：CF 1与下降的SC相关联; CF2位于PC的东部; CF 3位于PC核心的西部。星团外围的另外两个边缘是激波锋面（SF）：西北方向RR附近的SF 1的马赫数分别来自$M_T=1.62\pm0.12$和$M_ρ=1.23\pm0.06$的温度和密度跃变;东南方向的SF 2有$M_T=1.54\pm0.05$和$M_ρ=1.16\pm0.13$。在RR区域，没有证据表明X射线和射电子结构之间存在相关性，因此我们估计了逆康普顿发射的上限，并因此将磁场的下限（$\sim$距离PC中心450 kpc）设定为$B>1.0\ μ$ G（对于单个幂律电子谱）或$B>0.4\ μ$ G（对于破碎的幂律电子谱）。我们提出了一个合并的情况下，包括PC，SC，和一个组。我们的合并方案占X射线边缘，漫射射电特征，星系运动学，以及投影效果。
英文摘要：
We present the results of deep Chandra and XMM-Newton observations of a complex merging galaxy cluster Abell 2256 (A2256) that hosts a spectacular radio relic (RR). The temperature and metallicity maps show clear evidence of a merger between the western subcluster (SC) and the primary cluster (PC). We detect five X-ray surface brightness edges. Three of them near the cluster center are cold fronts (CFs): CF1 is associated with the infalling SC; CF2 is located in the east of the PC; and CF3 is to the west of the PC core. The other two edges at cluster outskirts are shock fronts (SFs): SF1 near the RR in the NW has Mach numbers derived from the temperature and the density jumps, respectively, of $M_T=1.62\pm0.12$ and $M_ρ=1.23\pm0.06$; SF2 in the SE has $M_T=1.54\pm0.05$ and $M_ρ=1.16\pm0.13$. In the region of the RR, there is no evidence for the correlation between X-ray and radio substructures, from which we estimate an upper limit for the inverse-Compton emission, and therefore set a lower limit on the magnetic field ($\sim$ 450 kpc from PC center) of $B>1.0\ μ$G for a single power-law electron spectrum or $B>0.4\ μ$G for a broken power-law electron spectrum. We propose a merger scenario including a PC, an SC, and a group. Our merger scenario accounts for the X-ray edges, diffuse radio features, and galaxy kinematics, as well as projection effects.
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