XMM-Newton confirmation of soft X-ray excess emission in clusters of galaxies - The discovery of O VII emission from an extended warm baryonic component
XMM-Newton confirmation of soft X-ray excess emission in clusters of galaxies - The discovery of O VII emission from an extended warm baryonic component
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XMM-牛顿证实星系团中的软 X 射线过量发射 - 发现来自扩展的暖重子成分的 O VII 发射
DOI：
10.1051/0004-6361:20021514
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发表时间：
2002
影响因子：
6.5
通讯作者：
J. Herder
中科院分区：
文献类型：
--
作者：
J. Kaastra;Richard Lieu;T. Tamura;F. Paerels;J. Herder
我们研究了xmm -牛顿观测到的14个星系团样本，以寻找软x射线过量辐射。在其中五个集群中，明显存在明显的软过剩。将这种软x射线过剩与来自团内热气体和可能存在的任何冷却（流动）气体的热发射进行比较。一个温暖的（kT = 0.2 keV），扩展的（几个Mpc）等离子体成分在星团的外部特别清晰，在那里正常的星团x射线发射很弱。这个温暖的成分导致了低能（低于0.4-0.5 keV）的热软x射线过剩，以及O线发射，其红移与星团起源一致，不容易被解释为银河系前景发射。该组件的强度与之前用ROSAT PSPC在1/4 keV波段测量的强度相称。我们将这一成分归因于这些星团附近的暖热星系间介质的星团间细丝的发射。对于星团的中心区域，软x射线谱线的探测更加困难，因为x射线发射的热等离子体在那里占主导地位，因此我们无法区分软过剩的热源和非热源，留下了几个选择。这些包括在星团中心前后投射的温暖细丝的热辐射，星团核心本身与磁重联有关的热辐射或非热辐射，或宇宙微波背景在相对论性电子上的逆康普顿辐射。
We investigate a sample of 14 clusters of galaxies observed with XMM-Newton in a search for soft X-ray excess emission. In five of these clusters a significant soft excess is evident. This soft X-ray excess is compared with the thermal emission from both the hot intracluster gas and any cooling (flow) gas that may be present. A warm (kT = 0.2 keV), extended (several Mpc), plasma component is particularly clear in the outer parts of the cluster, where the normal cluster X-ray emission is weak. This warm component causes both a thermal soft X-ray excess at low energies (below 0.4-0.5 keV), as well as O line emission with a redshift consistent with a cluster origin, and not easily interpreted as Galactic foreground emission. The intensity of this component is commensurate with what has been measured before with the ROSAT PSPC in the 1/4 keV band. We attribute this component to emission from intercluster filaments of the Warm-Hot Intergalactic Medium in the vicinity of these clusters. For the central regions of clusters the detection of lines in the soft X-ray spectrum is more difficult, due to the predominance of the X-ray emitting hot plasma there, hence we cannot discriminate between the thermal and nonthermal origin of the soft excess, leaving several options open. These include thermal emission from warm filaments seen in projection in front of or behind the cluster center, thermal or nonthermal emission in the cluster core itself related to magnetic reconnection, or Inverse Compton emission from the cosmic microwave background on relativistic electrons.