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首页> 外文期刊>The Astrophysical journal >LONG-TERM SPECTRAL VARIABILITY OF SEYFERT GALAXIES FROM ROSSI X-RA Y TIMING EXPLORER COLOR-FLUX DIAGRAMS
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LONG-TERM SPECTRAL VARIABILITY OF SEYFERT GALAXIES FROM ROSSI X-RA Y TIMING EXPLORER COLOR-FLUX DIAGRAMS

机译：ROSSI X-RA Y时序探索者色通量图表示的塞弗特星系的长期光谱变异性

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摘要

We present results from Rossi X-Ray Timing Explorer data obtained during a systematic monitoring program of four Seyfert galaxies (NGC 5548, NGC 5506, MCG -6-30-15, and NGC 4051). We studied the vari-ability of three hardness ratios derived from the light curves in four energy bands (HR1, which describes the continuum variations, and HR2 and HR3, which are sensitive to the iron line and reflection component variations with respect to the continuum, respectively). All the objects show similar spectral variations in all ratios. In order to interpret the results we computed the hardness ratios corresponding to a simple spectral model of a power law plus iron line plus reflection component. In order to derive the model HR2 and HR3 colors, we considered two possibilities: (1) variations with constant line equivalent width and reflection parameter R (the case of a reflecting/reprocessing material that responds with a short delay to the continuum variability) and (2) variations with constant line and reflection flux (the case of a reprocessor that does not respond to the fast, intrinsic variations). The overall, mean observed trends can be explained by spectral slope variations (ΔΓ approx= 0.2-0.3, and approx= 1 for NGC 4051) and a constant-flux Fe line and reflection component, although the existence of a line component that is variable on short timescales cannot be excluded. Finally, we find that the data are not consistent with an increase of R with flux for individual sources, indicating that, as a single source varies, softer spectra do not correspond to larger R values.
机译：我们介绍了在四个塞弗特星系（NGC 5548，NGC 5506，MCG -6-30-15和NGC 4051）的系统监视程序中获得的Rossi X射线定时资源管理器数据的结果。我们研究了从四个能带中的光曲线得出的三个硬度比的可变性（HR1描述了连续谱变化，HR2和HR3对铁线和反射分量相对于连续谱变化敏感，分别）。所有物体在所有比率上都显示出相似的光谱变化。为了解释结果，我们计算了对应于幂律，铁线和反射分量的简单光谱模型的硬度比。为了得出模型HR2和HR3的颜色，我们考虑了两种可能性：（1）具有恒定线等效宽度和反射参数R的变化（反射/后处理材料对连续性变化具有短暂延迟的情况）和（2）具有恒定线和反射通量的变化（洗消机不响应快速的固有变化）。总体平均观测趋势可以通过频谱斜率变化（ΔΓ大约为0.2-0.3，对于NGC 4051大约为1）和恒定磁通的Fe线和反射分量来解释，尽管存在可变的线分量在短时间内无法排除。最后，我们发现数据与单个光源的R随着通量的增加而不一致，这表明，随着单个光源的变化，较软的光谱并不对应于较大的R值。

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