X-ray spectral variability in the ultraluminous X-ray source Holmberg IX X−1
X-ray spectral variability in the ultraluminous X-ray source Holmberg IX X−1
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DOI：
10.1111/j.1365-2966.2009.16210.x
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发表时间：
2009-12
影响因子：
4.8
通讯作者：
K. Vierdayanti;C. Done;T. Roberts;S. Mineshige
中科院分区：
文献类型：
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作者：
K. Vierdayanti;C. Done;T. Roberts;S. Mineshige
我们使用XMM-牛顿和雨燕数据来研究超亮X射线源（ULX）Holmberg IX X−1的光谱变化。光源的光度变化为3-4倍，引起相应的光谱变化，这些变化是显著的，但很微妙，并且不能很好地通过简单的硬度比来跟踪。相反，我们共同添加强度箱中的Swift数据，并使用圆盘加热康普顿化模型进行全光谱拟合。所有的数据都很好地拟合了低温，光学厚康普顿电晕，和可变性可以大致的特点是降低温度和增加光学深度的源变得更亮，如预期的那样，如果电晕逐渐成为质量加载的材料吹离超爱丁顿内盘。在具有类似光谱的其他ULX中观察到这种可变性行为，但与在具有更软光谱的ULX中观察到的趋势相反。这支持了ULX中存在两种不同的物理机制的想法，其中光谱从由盘状日冕主导到由风主导。
We use XMM–Newton and Swift data to study a spectral variability in the ultraluminous X-ray source (ULX), Holmberg IX X−1. The source luminosity varies by a factor of 3–4, giving rise to corresponding spectral changes which are significant, but subtle, and not well tracked by a simple hardness ratio. Instead, we co-add the Swift data in intensity bins and do full spectral fitting with disc plus thermal Comptonization models. All the data are well fitted by a low temperature, optically thick Comptonizing corona, and the variability can be roughly characterized by decreasing temperature and increasing optical depth as the source becomes brighter, as expected if the corona is becoming progressively mass loaded by material blown off the super-Eddington inner disc. This variability behaviour is seen in other ULX which has similar spectra, but is opposite to the trend seen in the ULX with much softer spectra. This supports the idea that there are two distinct physical regimes in ULXs, where the spectra go from being dominated by a disc-corona to being dominated by a wind.