The flux-dependent X-ray time lags in NGC 4051
The flux-dependent X-ray time lags in NGC 4051
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DOI：
10.1093/mnras/stt1391
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发表时间：
2013-07
影响因子：
4.8
通讯作者：
W. Alston;S. Vaughan;P. Uttley
中科院分区：
文献类型：
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作者：
W. Alston;S. Vaughan;P. Uttley
我们基于 2009 年进行的一系列 XMM-Newton 观测，对高度可变的 Seyfert 1 星系 NGC 4051 的 X 射线时滞进行了分析。我们研究了 0.3-1.0 keV 和 2.0-5.0 keV 能带之间的光变曲线中傅里叶频率相关的时滞作为源通量的函数，包括对所得滞后频谱的同步建模。我们发现滞后频谱的形状随源通量显着且系统地变化。我们使用简单的传递函数对滞后频谱进行建模，发现需要两个时间滞后分量，每个能带一个。最简单的可接受的拟合仅具有硬带中滞后分量随通量水平变化的相对贡献，这可以与能谱的变化相关。我们根据当前流行的 X 射线时滞模型讨论这些结果的解释。
We present an analysis of the X-ray time lags for the highly variable Seyfert 1 galaxy NGC 4051, based on a series of XMM-Newton observations taken in 2009. We investigate the Fourier frequency dependent time lags in the light curves between the 0.3-1.0 keV and 2.0-5.0 keV energy bands as a function of source flux, including simultaneous modelling of the resulting lag-frequency spectra. We find the shape of the lag-frequency spectra to vary significantly and systematically with source flux. We model the lag-frequency spectra using simple transfer functions, and find that two time lag components are required, one in each energy band. The simplest acceptable fits have only the relative contribution of the lagged component in the hard band varying with flux level, which can be associated with changes in the energy spectrum. We discuss the interpretation of these results in terms of the currently popular models for X-ray time lags.