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arXiv 1010.3840astro-ph.CO
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星系团A3112中X射线过量发射的朱雀观测

Suzaku observations of X-ray excess emission in the cluster of galaxies A3112

T. Lehto, J. Nevalainen, M. Bonamente, N. Ota, J. Kaastra

摘要:

我们分析了A3112星系团的朱雀XIS 1数据,以检查该星系团的X射线过量发射,在此之前报告的XMM-牛顿和钱德拉卫星。团内气体的最佳拟合温度在很大程度上取决于光谱分析所用能带的选择。这证明了A3112中除了单温MEKAL外,还存在过量发射成分。我们表明,这种效应不是由于背景建模,仪器校准或银河系吸收量的不确定性造成的伪影。冷核辐射的点扩散函数散射和冷气体在星系团外围的投射都不产生这种效应。最后,我们模拟过量排放,无论是通过使用一个额外的MEKAL或幂律分量。由于热模型和非热模型之间的差异很小,我们不能根据拟合优度排除过量排放的非热来源。假设它有一个热的起源,我们进一步研究了差分排放测量(DEM)模型。我们利用了两种不同的DEM模型,高斯差分排放测量分布(GDEM)和WDEM模型,其中一些热组件的排放测量分布为截断幂律。0.4-7.0 keV带的最佳拟合XIS 1 MEKAL温度为4.7 ± 0.1 keV,与使用GDEM和WDEM模型获得的结果一致。

英文摘要:

We analysed the Suzaku XIS1 data of the A3112 cluster of galaxies in order to examine the X-ray excess emission in this cluster reported earlier with the XMM-Newton and Chandra satellites. The best-fit temperature of the intracluster gas depends strongly on the choice of the energy band used for the spectral analysis. This proves the existence of excess emission component in addition to the single-temperature MEKAL in A3112. We showed that this effect is not an artifact due to uncertainties of the background modeling, instrument calibration or the amount of Galactic absorption. Neither does the PSF scatter of the emission from the cool core nor the projection of the cool gas in the cluster outskirts produce the effect. Finally we modeled the excess emission either by using an additional MEKAL or powerlaw component. Due to the small differencies between thermal and non-thermal model we can not rule out the non-thermal origin of the excess emission based on the goodness of the fit. Assuming that it has a thermal origin, we further examined the Differential Emission Measure (DEM) models. We utilised two different DEM models, a Gaussian differential emission measure distribution (GDEM) and WDEM model, where the emission measure of a number of thermal components is distributed as a truncated power law. The best-fit XIS1 MEKAL temperature for the 0.4-7.0 keV band is 4.7+-0.1 keV, consistent with that obtained using GDEM and WDEM models.

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