arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1302.4140astro-ph.COastro-ph.HE
收藏

后发座星系团外围的热力学

Thermodynamics of the Coma Cluster Outskirts

A. Simionescu, N. Werner, O. Urban, S. W. Allen, A. C. Fabian, A. Mantz, K. Matsushita, P. E. J. Nulsen, J. S. Sanders, T. Sasaki, T. Sato, Y. Takei, S. A. Walker

摘要:

我们目前的结果从一个大的马赛克朱雀观测后发座星系团,最近的和X射线最亮的热,动态活跃,非冷的核心系统,集中在大尺度上的ICM的热力学性质。对于方位角不对准一个落向西南的子集群,我们测得的温度和X射线亮度分布表现出广泛一致的径向趋势,温度从约8.5千电子伏的集群中心约2千电子伏的半径为2百万秒差距,这是我们的检测极限的边缘。SW合并显着提高了表面亮度,使我们能够沿着这个方向探测到约2.2 Mpc的X射线发射。除了西南下沉的子星系团,表面亮度剖面显示出多个半径为30-40弧分的边缘。的方位平均温度分布,以及deprojected密度和压力分布,都显示出一个急剧下降一致的向外传播的冲击波前位于40弧分,对应的巨型射电晕的最外边缘观察到在352 MHz的WSRT。冲击波阵面可能是无线电发射的能量来源。r_500内部的明显熵过剩反映了与这些形态特征相关的剧烈合并事件。在r_500以上,后发座星系团沿相对松弛方向的熵分布与引力大尺度结构形成的简单模型所预期的幂律行为一致。在这些半径处的压力也与从普朗克卫星的SZ数据测量的预期值一致。然而,由于后发座星系团的测量结果存在很大的不确定性,我们还不能排除这个系统中的熵变平现象,这与在更宽松的冷核星系团中看到的熵变平现象是一致的。

英文摘要:

We present results from a large mosaic of Suzaku observations of the Coma Cluster, the nearest and X-ray brightest hot, dynamically active, non-cool core system, focusing on the thermodynamic properties of the ICM on large scales. For azimuths not aligned with an infalling subcluster towards the southwest, our measured temperature and X-ray brightness profiles exhibit broadly consistent radial trends, with the temperature decreasing from about 8.5 keV at the cluster center to about 2 keV at a radius of 2 Mpc, which is the edge of our detection limit. The SW merger significantly boosts the surface brightness, allowing us to detect X-ray emission out to ~2.2 Mpc along this direction. Apart from the southwestern infalling subcluster, the surface brightness profiles show multiple edges around radii of 30-40 arcmin. The azimuthally averaged temperature profile, as well as the deprojected density and pressure profiles, all show a sharp drop consistent with an outward propagating shock front located at 40 arcmin, corresponding to the outermost edge of the giant radio halo observed at 352 MHz with the WSRT. The shock front may be powering this radio emission. A clear entropy excess inside of r_500 reflects the violent merging events linked with these morphological features. Beyond r_500, the entropy profiles of the Coma Cluster along the relatively relaxed directions are consistent with the power-law behavior expected from simple models of gravitational large-scale structure formation. The pressure is also in agreement at these radii with the expected values measured from SZ data from the Planck satellite. However, due to the large uncertainties associated with the Coma Cluster measurements, we cannot yet exclude an entropy flattening in this system consistent with that seen in more relaxed cool core clusters.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑