Possible non-thermal nature of the soft-excess emission in the cluster of galaxies Sérsic 159-03
Possible non-thermal nature of the soft-excess emission in the cluster of galaxies Sérsic 159-03
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Sérsic 159-03 星系团中软过剩发射的可能非热性质
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
T. Tamura
中科院分区：
文献类型：
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作者：
Norbert Werner;J. Kaastra;J. Kaastra;Y. Takei;Richard Lieu;Jacco Vink;T. Tamura
我们分析了SERSIC159-03星系团的新的Suzaku数据和来自XMM-牛顿的档案数据，该星系团具有很强的软X射线超额发射成分。Suzaku的观测证实了软过量发射的存在，但没有证实星系团中存在红移的Ovii线。由XMM-牛顿观测得到的径向轮廓和二维图表明，软超额发射在CD星系中心位置有一个很强的峰值，并且图上没有显示出任何明显的方位变化。尽管热模型和非热模型都能很好地拟合软超额辐射，但它的空间分布与星系团间的暖热丝模型不一致，也与星系团下落的团块状温暖星团内气体模型不一致。利用XMM-牛顿反射光栅谱仪获得的数据，我们不能证实星团中心有热气体的存在，而假定软过剩是热源。观测到的软过量发射特性与非热学解释相一致。虽然与星团中心软发射峰值相关的高密度相对论电子可能是由CD星系中心的活动星系核提供的，但底层人口可能在扩散激波中加速。
We present an analysis of new Suzaku data and archival data from XMM-Newton of the cluster of galaxies Sersic 159-03, which has a strong soft X-ray excess emission component. The Suzaku observation confirms the presence of the soft excess emission, but it does not confirm the presence of redshifted Ovii lines in the cluster. Radial profiles and 2D maps derived from XMM-Newton observations show that the soft excess emission has a strong peak at the position of the central cD galaxy and the maps do not show any significant azimuthal variations. Although the soft excess emission can be fitted equally well with both thermal and nonthermal models, its spatial distribution is neither consistent with the models of intercluster warm-hot filaments, nor with models of clumpy warm intracluster gas associated with infalling groups. Using the data obtained by the XMM-Newton Reflection Grating Spectrometers we do not confirm the presence of the warm gas in the cluster centre with the expected properties assuming the soft excess is of thermal origin. The observed properties of the soft excess emission are consistent with the non-thermal interpretation. While the high density of relativistic electrons associated with the peak of the soft emission in the cluster centre might have been provided by an active galactic nucleus in the central cD galaxy, the underlying population might have been accelerated in diffuse shocks.