标题： $Suzaku$和$XMM-Newton$对新发现的早期阶段星系团合并 1E2216.0-0401 和 1E2215.7-0404 的观测 显示英文标题

标题： $Suzaku$ and $XMM-Newton$ observations of a newly-discovered early-stage cluster merger 1E2216.0-0401 and 1E2215.7-0404

摘要： 我们展示了对星系团对1E2216.0-0401和1E2215.7-0404的$Suzaku$和$XMM-Newton$X射线观测结果。 我们发现星系团之间存在X射线桥。 $Suzaku$和$XMM-Newton$观测结果表明，每个星系团都拥有温度适中的气体，分别为$kT_{1E2216.0-0401}=$4.8$\pm$0.1 keV 和$kT_{1E2215.7-0404}=$5.8$\pm$0.2 keV。 另一方面，桥区域显示出显著的高温（{\it kT}=6.6$\pm$0.5 keV）。 此外，在桥的位置，我们在小波分解的软能段（0.5-4.0 keV）$XMM-Newton$图像中检测到3倍标准差的增强，这很可能是因为合并活动导致的星系团内介质（ICM）的压缩。 这种X射线强度和温度增强与晚期阶段的预期不一致，但与早期阶段合并的数值模拟预测一致。 根据桥位置的温度跳跃，马赫数估计为${\cal M}=1.4\pm0.1$，这对应于约1570 km/s的激波传播速度。 根据激波特性，我们估计核心通过将在0.3-0.6 Gyr内发生，且激波结构的年龄为50--100 Myr。 基于桥处ICM的测量特性和时间尺度的估计，我们发现非平衡电离的迹象。 我们还发现了位于合并星系团之间的可能弥散射电发射。 结合射电、X射线和光学图像数据，我们推测检测到的射电源很可能与合并事件有关。 因此，1E2216.0-0401和1E2215.7-0404是一个具有显著特征的早期阶段星系团合并的新例子。 显示英文摘要

摘要： We present the results of $Suzaku$ and $XMM-Newton$ X-ray observations of the cluster pair 1E2216.0-0401 and 1E2215.7-0404. We discover an X-ray bridge between the clusters. $Suzaku$ and $XMM-Newton$ observations revealed that each cluster hosts gas with moderate temperature of $kT_{1E2216.0-0401}=$4.8$\pm$0.1 keV and $kT_{1E2215.7-0404}=$5.8$\pm$0.2 keV, respectively. On the other hand, the bridge region shows a remarkably high temperature ({\it kT}=6.6$\pm$0.5 keV). Furthermore, at the position of the bridge, we detected an enhancement in the wavelet-decomposed soft-band (0.5-4.0 keV) $XMM-Newton$ image at 3 sigma significance, this is most likely due to a compression of the intracluster medium (ICM) as a consequence of the merging activity. This X-ray intensity and temperature enhancement are not consistent with those expected from a late phase, but are in agreement with the predictions by numerical simulations of an early phase merger. From the temperature jump at the location of the bridge, the Mach number is estimated to be ${\cal M}=1.4\pm0.1$, which corresponds to a shock propagation velocity of about 1570 km/s. From the shock properties, we estimate that core-passage will occur in 0.3-0.6 Gyr and that the age of the shock structure is 50--100 Myr. Based on the measured properties of the ICM at the bridge and estimation of timescales, we find indications for non-equilibrium ionization. We also discover possible diffuse radio emission located between the merging clusters. Combining the radio, X-ray, and optical image data, we speculate that the detected radio sources are most likely related to the merger event. Thus, 1E2216.0-0401 and 1E2215.7-0404 is a new example of an early phase cluster merger with remarkable characteristics.